Web Site: http://www.airdorrin.com
Posts by fdorrin:
- Cylinders #1 and #3 peak simultaneously and the fuel flow spread was 0.7 gph
- 8.4 gph will yield 100o ROP at 65% power in this run
- LOP operation: 6.3 gph will get me on the LOP side where all cylinders have peaked and have EGTs declining as we get leaner. This would have been 10o LOP on this test, but Mike Busch doesn’t care where the peak is. CHTs are what matters, and those are all less than 380 in this scenario. Cylinder #4 was the hottest, but I suspect we’ll be more golden there now.
I heard from JPI regarding my replacement temperature probes. I am a bit disappointed that they didn’t run to the mailbox and send out new probes. Instead, they asked me to send them the POs and Invoices and questioned how long I’ve owned them. That made me go back to my A&P and have them do that research for me, which adds times. I gave JPI some lip that they should be able to look that up on their own and not be giving me homework. So far JPI is giving me attitude rather than support.
Reviewing the last GAMI test to harvest more data is fascinating. What the heck did I do without an engine monitor? What was I thinking? Then again – you don’t know what you don’t know.
Here are some interesting tidbits from the left engine I’ve observed that will help set up the next test. It is generally the same for the right side.
The next Test: I wanted to fly after work today, but have since seen that the weather south of us will not be all that great. I’ll wait a bit and do a flight down to Norfolk with a stop on the way back at Georgetown for gas. I’m looking forward to gathering some good intel on how best to operate these engines for allot of flying I have planned in July. I will not be operating LOP operations for this oil change, but I’ll gather data to get ready. Paul suggests I keep it ROP for another 50 hours.
N833DF Test Profile
- Climb to 6000′
- Lean as necessary on the way up to maintain 400o F on all cylinders
- Reaching 6000′ in level cruise, note the OAT against 38o C standard. Plan on adjusting MP (see below for details)
- Set power 24 squared, close cowl flaps, lean to 400o F and note the fuel flow
- Set power 23 squared, closed cowl flaps, lean to 400o F and note the fuel flow
Note: Leave the mixture there as a starting point for the GAMI test
- Begin GAMI Lean Test – one engine at a time
- Open Cowl Flaps
- Verify props to 2300 RPM and MP to 21.6″ +/- OAT adjustment
- Lean slowly (0.2 to 0.3 gph increments)
Note: Test is complete after all EGTs continue to drop as you decrease fuel flow with the mixture
- Determine LOP Range: Continue leaning slowly right up to engine roughness.
- Note the fuel flow. Expect cut-out at 5.7gph
- Enrich to smooth operation. Try 6.0 gph specifically.
That is it for what I’m trying to accomplish. What follows is my thinking behind this profile. if you see a flaw in that thinking, please speak up. I plan to use the video to both share and to supplement the recorded data.
1. ROP Operation: Right off the bat, reaching 6000′ let’s determine what fuel flow looks like for a CHT of 400o F on all cylinders. Keep in mind that fuel injectors, temperature probes, and baffle seals have all changed. Do this for both 24 squared and 23 squared operation.
Note: I see definite improvement in cylinder head temperatures now, but would love to know where the improvements came from. Did the physical repositioning of the probe knock the problem out of the probe or connection for left CHT#4? Did the baffle improvement really drop Cylinder #4 by 30o F? I have to assume at this point that sealing up the air leaks in the baffles made that big difference. Paul did that work on both sides.
Note: without an engine monitor – I’d be flying along and possibly toasting one of my cylinders. Continuously.
2. GAMI Lean Test: This requires a climb to an altitude that ensures I stay at 65% power, the recommended power setting for the GAMI Lean Test. From the PA30 POH, you can see that 6000′ will generally work. From the two charts below I determine that 65% power can be achieved using 2300 RPM and 21.6″ MP, This will keep me just inside the Red Fin for most of the process. I’ll never be in a truly abusive zone with high internal cylinder pressures.
Power (MP) must be adjusted by 0.17″ for every 10o F above standard temps at that altitude, or lower by the same amount for temps below standard. Standard temp at 6000′ is 3o C or 38o F.
The method I will use from the GAMI site is the download method, since I have an engine monitor with integral fuel flow and downloading capabilities. In flight at 2300 RPM and 21.6″ MP, lean very slowly from some point rich of peak EGT to some point where all EGTs are lean of peak. You will know that you are lean of peak EGT on all cylinders once the exhaust temperature of each cylinder continues to drop as you reduce the fuel flow.
I am going to continue the leaning process right through to LOP operation and engine roughness. That will tell me everything – minimum fuel flow at smooth operation LOP; what fuel flow leads to the engine running rough or cutting out; the GAMI fuel spread; and even where ROP fuel flow is. I just need to do it slowly enough to gather meaningful data, all the while keeping CHTs below 400o F.
I’ll publish this post, and then go to the SavvyAviation website and analyze the previous GAMI Lean Test for what it can tell me.
Comments Off on Jun 16, 2020 – N833DF Follow-up Test Profile
Oil Change Complete! I dropped off the airplane yesterday morning, and both Paul and Ralph jumped on the work and completed it in one day. You can see the squawk list on yesterdays blog, so I’ll just focus on the highlights today.
The cowls on both engines were removed and all mounts, mounting points, fasteners, and general conditions were checked once again. Two of the exhaust mounts (straps with metal end caps) were brand new and both failed. These are WEBCO PMA units that run $56 apiece.
The issue was reported to WEBCO. Two new ones were installed and I’ll be looking for money back from them soon. If these new ones fail as well, we’ll get the piper part installed and report the issue. Minor point that doesn’t affect my flying. No other issues were found. No leaks and no looseness.
On the left engine, CHT #3 had been erratic. You can see here that the brown line is CHT#3 zooming up over the red line (450 deg F), and then right back to normal. This was from a flight on June 6th. On other flights, the CHT #3 went to +700 F and right back down to -90 F. At least I knew with great certainty THAT wasn’t happening.
Paul replaced all the connectors in the CHT#3 line to rule out crushed and shorted connections. The character of the anomalies changed for this latest flight, with the CHT dropping to zero, but the issue remains. JPI has been directly asked to replace this probe.
Next up was the issue of the left cylinder #4 being so damn hot that I have to shallow out climbs and reduce power in cruise. On JPI’s suggestion, we swapped the #4 probe and the #2 probe. Now here is where it gets a little sticky. The temperature problem did move to cylinder #2 in that it is now the hottest cylinder. It gets complicated though, as the guys did quite a bit of work sealing up all my new baffles.
With the cowls off, both engine baffle systems were re-inspected and fireproof sealant was added to seal off potential leaks and maximize airflow for cooling. I didn’t expect any noticeable improvement from this, but Paul wanted to try it.
As you can see from yesterdays flight, all temps now are in range and reasonable (except CHT #3 of course). The climb was unrestricted on a hot day and never got much above 400F. Wow! That was nice! I closed the cowl doors for the entire flight.
As a result, I asked JPI to replace both the erratic and the hot probe based on these results. I included the ‘hot probe’ as well because it was just a bit hotter on this flight than previous flights. If they send me only one probe I’ll be ok, since It could reasonably be argued that the sealed up baffles caused the temperature to drop on cylinder #4.
I’m now on 100W oil with CamGuard and have 50 hours to play with it. I’m working in Texas in July, and considering flying. Storm damage is my real concern there, while it sits on the ramp. Both trips are relatively short, and I’m seriously considering avoiding the airlines and flying myself.
No squawks today, other than I left bugs on it last night and the spinners really need to be polished. I’ll get to that work soon.
Fly Safe! Frank
Comments Off on Jun 12, 2020 – Oil Change and Re-inspection
Sorry – I couldn’t resist talking in phases with all this virus stuff still holding us back. I have been busy at work and too lazy to fly after working all day. The heat, humidity, and thunderstorms have been part of that equation too. I cannot blame the winds, as seem to be a bunch gusting to a bunch more every time I open the hangar door. My crosswind skills have been sharpened, but I am tending to land fast all the time. For now, I won’t be getting off at the first taxiway.
So my A&P, Paul, reached out last week to see how I was doing burning hours towards the next oil change. We have some issues to address on the Penn Yan engine work, and in general, and apparently he knew he’d have some time to address them. I had to get moving if I was going to get the full 30 hours in so we could change out of mineral oil.
Where do we stand: Oil consumption has been great. I put in 2 quarts of 100W mineral oil in 30 hours on the right side and 1.5 quarts in 30 hours on the left. Operation has been smooth, which is EXCELLENT!. The climbs, however, must be kept shallow with power reduced fairly soon to manage CHT#4 on the left side. That is an issue that needs to be pursued to a solution. (Suggestions? [email protected])
The GAMI Lean Test results were addressed by the GAMI folks, who sent us two new nozzles for cylinder #4 on both engines (no charge). The new nozzles will increase the heat when ROP, so that means I’ll be even more restricted in climbs if we do nothing else. They’ll run cooler LOP in cruise, so that’ll be good. In any event, I’m only expecting a 5 degree shift either way, per GAMI.
I’ll have to confirm this with Penn Yan and Mike Busch, but I think I can begin LOP operations after this oil change. That may actually resolve the heat issue in cruise, but that remains to be seen. I’ll be conducting another GAMI Lean Test after the new nozzles, to verify the improvement. See the GAMI Lean Test Procedure here.
Paul will be pulling off all the cowls and inspecting mounts, connections, and everything else as a matter of course. While they are all off, I’ve given him a summary of the work I see that needs to be accomplished.
1. Oil Analysis: Blackstone oil analysis starts with this change. Paul suggested waiting one more phase, but I’ll start that now.
2. Left engine Throttle movement restriction: Left engine fuel flow is lower than right. This reduces fuel available for cooling at take-off, exacerbating the already hot cyl #4 issue.
3. GAMI Fuel Nozzles: Install new fuel nozzles per the GAMI lean test
John-Paul Townsend from GAMI writes: On your left engine, #1 peaks first at 7.2 gph and #4 is last at 6.5 gph. That is a 0.7 gph spread. We really want that to be under 0.5 gph. The other two peak at 6.9 gph, so we should make #4 leaner. That will make #4 CHT cooler while you are LOP and warmer while you are ROP, but not more than about 5°F either way. The right engine is almost identical. Two new nozzles are on the way.
4. JPI Repair: I’ve got a definite issue with CHT#3 and a possible issue with CHT#4
Left Cylinder #3 CHT is erratic. JPI suspects crushed wires at a clamp causing a short
Left Cylinder #4 is 30 degrees hotter and requires shallow climbs and open cowl door in level flight. This may be an airflow issue, a Penn Yan issue, a JPI issue, or a GAMI issue. We will eliminate one at a time. Tim Sullivan from JPI recommends:
– Disconnect the one wire from the factory CHT probe on the # 3 cyl. If probe bad or not grounded well, reading can become erratic.
– #4 CHT, leave probes where they are mounted and swap wires with adjacent cylinder, if problem moves the bad probe.
5. Gear door crack: Check small gear door crack near hinge rivet-stop-drill
6. Oil change and general inspection: We’ll be using 100W straight weight oil with CamGuard.
7. Cyl #4 Heat issue: check BAFFLES for the cause of left cylinder #4 heat (air leaks). Take pictures of both engines so I can explain baffles to others. Swap the temperature probes between #2 and #4. Repair the CHT#3 issue.
8. Struts are dirty: Their extension is good, but I didn’t clean them so you could evaluate for leaks.
Running the Engines: Ok – so we know what we’ll be working on. I’m hoping I can get all the squawks out of the way and just focus on CHT#4 being hot. In the mean time though, I needed to run off the remaining hours. As of the last post on May 30th, I had 10.2 hours remaining in the Phase II 30 hour mineral oil run. I began feeling the pressure to ensure I have recent experience in cross country and instrument flights as well, given that I may be taking the wife in our airplane to Florida in July. It’s been too long since I’ve dodged storms and flown actual IMC in this machine, too long.
On June 5th I flew for 2.2 hours with storms in the area and strong winds. I intended to do this flight VFR, mostly due to the storms being embedded at times. The plan was to fly to Ocean City, Maryland for a few practice approaches in VFR. After that I’d fly to Salisbury, Maryland for a few more and then home to Wilmington. I watched the weather as I flew south and it became clear I would’t make it home VFR today.
Since I hadn’t filed a flight plan today, I opted to land at Ocean City and use my phone to file IFR from Salisbury to Wilmington. ForeFlight really improved the iPhone interface to make that easy. I then flew to Salisbury and did an approach there to a low approach, picking up my clearance on the go. It was becoming clear that developing storms in Wilmington might preclude me from getting back home even IFR, so I headed north after only one approach.
Landing at Wilmington was in gusting winds and MVFR ceilings with a storm cell 10nm north of the field. Total flight time 2.2 hours with 0.7 IMC. It began to rain as I closed the hangar door.
On Saturday, June 6th, my wife was busy. My plan was to fly for 2+ hours both Saturday and Sunday, getting closer to the oil change time. Then I found out that my wife had convinced several of her siblings to provide care for my elderly mother in-law on Sunday, and Bev was ready to get out of the house. She is an angel for doing what she does every day, and I wouldn’t think of being busy when she can get out.
I canceled flying for Sunday to make our day out happen, and decided I needed to fly longer on Saturday. I’d been talking with a fellow PA30 owner recently about maybe meeting halfway somewhere for lunch. We are both in the same boat – not having flown the airplanes recently and with voluntarily raised personal minimum. Jim lives in Atlanta, one of my favorite towns. I decided to drop in for a visit. Bev packed me a lunch and I was off.
Storms were expected, and the area was mountainous, but I had that Florida trip coming up and I wanted recent cross country experience. I launched on what would be 8.9 hours of flying, down and back. I made a few mistakes along the way, but the airplane was flawless. I will say I ran the entire trip ROP at reduced power to manage heat. Still made what I consider great time, when you include a stop for cheap fuel in there.
One notable pilot error was stopping for gas at an unfamiliar airport. Cherokee County (KCNI) is in the middle of hills and terrain, and has one hell of a slope landing west (rwy 23). It also has cheap gas, which apparently drew every cessna and piper airplane into it’s pattern. It was a bit distracting hearing all these aircraft (5 or six at once) in the pattern call out ‘Cessna 123 left downwind 23 Cherokee’. By the time I entered the pattern I was number 3 and could only see one of the aircraft in front of me.
I got the gear down early, but my mistake was in NEVER running my GUMPS check. This is part of my nature, but I got busy looking for traffic and it dropped off. I’m working hard to find traffic and two airplanes are waiting to depart. With a start!, I realized my omission on short final and stole a glance out at the mirror to verify gear down. Since I wasn’t looking forward, I didn’t see the runway slope filling my windscreen until the last moment. My landing was reasonable, but I only saved it in the last few seconds (that is what if felt like anyway). On a good note – I heard several compliments like ‘Nice Twin’ on short final. I never looked at the AFD and was not aware of that significant slope. DUMB, DUMB, DUMB.
On Saturday, June 10th, I had completed the Phase II hours and was ready for my oil change. I made the short flight down to 33N, and my wife was freed up to come bring me home. As it turned out, Paul had an emergency and had left the field. He expected me to leave the airplane on the ramp, but I chose not to. Thunderstorms were in the area that night, and expected in the morning. I turned the wife around and flew back home. We’ll figure it out tomorrow.
On Saturday, June 11th, as I write this, the airplane has been delivered. Thunderstorms are expected; winds are gusting as usual; and low clouds are in the area. Wilmington airport has shortened hours, and the tower is closed until 8am. I filed an IFR flight plan for a 7am departure and picked it up easily on the ground with Philly departure. I climbed into the clouds around 1500′, heading for 4000′.
One of the reasons you need recency is learning to trust the instruments and the autopilot. The winds were 30-40 knots climbing through 2000′ and the drift bug and correction angle the autopilot was commanding looked wrong. I was communicating with Philly and watching the systems do their thing, while seriously considering disconnecting the A/P.
I reconsidered, figuring I could monitor course and attitude easily, and take it when I needed to. Instead, I wanted to verify it was working when I needed it to. The approach from that point, including clearance changes for the RNAV 27 into 33N from Blare, was absolutely flawless. I disconnected the automation around 900′ because I was getting bounced around in gusting winds, but flew the needles right to the ground. Good to know what is available in an emergency, and I’m confident I could rely on the airplane to get me where I needed to be.
That’s it for now. If you have the chance to fly an instrument approach before you start your workday – do that. I’m stoked with enough energy to make it fun all day.
Comments Off on Jun 10, 2020 – Phase III Flying
This past Saturday was one really nice day for me. The weather was very temperate and there were only a few clouds hanging out around 3000′. I’m still flying conservatively by avoiding flying IFR while I’m analyzing and pampering these new engines.
I had a nice breakfast with Beverly, as we watched the increasing pleasure boat traffic on the C&D canal. After that was all done, I pulled out the Harley, loaded up the cameras and my flight bag, and headed off to the airport.
Todays mission would be to fly to Atlantic City, perform two practice approaches, and then head southwest to Salisbury, Maryland. There I’d do a few more approaches before heading back to Wilmington, Delaware.
My engines are still being broken in. Actually, I think the right side is completely broken in while the left engine still has cylinder #4 making me wonder if its break in has been completed or not. Cylinder #4 continues to run 30 degrees hotter than everyone else, so I’m limiting power and maximizing airflow to control to that cylinder.
The JPI system is having an issue I’ve spoken about before. CHT probe #3 is definitely broken in some way. The CHT for that cylinder looks normal most of the time, but has momentary excursions from -90 deg F up to +600 deg F that’ll get your heart going. I have been given advice to look for a bad ground, but that is doubtful given the behavior of the system as a whole. I may be wrong here.
I spoke with JPI just now, since they didn’t respond to my email. They are confident that it is an installation issue, and will most likely be found at one of the clamps securing the wires. They want me to look for a crushed connection shorting the red and yellow wires together and involving this lead. An alternative would be to swap the probes to rule out a bad probe, though they said that probes either work 100% or not at all.
I’ll need to fly off 10 more hours to get the oil changed, swap the two probes (#3 and #4), and see what that gets me. These issues are solvable. By swapping those two probes, I’ll also be able to ensure that the hot cylinder #4 is actually hot and not a probe issue. I know, I know – the odds of finding an issue that fixes everything at once like this is nil. Worth a shot though.
Of course – if the probe I’m moving to #4 is actually bad – I’ll have a bad probe on a hot cylinder whose data I need. Let me think about that some more.
Todays Flying: Every now and then the stars line up and it is a wonderful day. I came out today knowing that the issues I’m running down are not threatening problems, and I can start expanding my use of my airplane. Today I’d be doing a few practice approaches, checking the data, and fine tuning my engine management for the next go. I already know I’ll be shallowing my climbs on go-around, to keep that #4 temp down.
I like the video I put together for this one….. I’m slowly improving my editing skills, I think.
The video link included here was only the first leg. The fun continued and included flying over the canal and my house on the way home. This was a very cool day indeed.
Comments Off on May 30, 2020 – One really good day!
As you know, I’ve been tracking an issue with the left engine CHT #3 reading. You can get a sense for what it’s doing looking at the graph to the left that spans over an hour. Notice the two blips around 22 minutes into the flight that suddenly rise maybe 50 degrees over where they were. The sudden rise is a spike that lasts only 1 reading. Readings at the time of the flight were set to occur every 6 seconds.
I never notice this has happened until I see an alarm around 37 or so minutes into the flight.
You can see where the CHT #3 reading spiked over the bright red line that is set to Lycoming’s limit of 450 degrees. Those readings persisted for only two or three six second samplings, and then dropped right back to normal. They stayed high only long enough to startle me, and then settled right back down to normal readings. I was able to observe the spastic fluctuations that continued to occur for the next few minutes (you can see them approaching alarm levels again at 42+ minutes), although I lost 200′ paying too much attention to them.
This graph looks to me like a loose connection, so I shortened the flight until I was able to look for those. My A&P suggested I remove a panel and check the connections. I’d come to the same conclusion and went over to the hanger yesterday morning (5/11/2020).
Click on the picture at left and you’ll see a good shot of what I was facing. No way I’m pulling things apart to look more closely. There was nothing amiss I could detect, so I called Paul. I did take a moment to reflect on how clean everything looked and enjoy the fact that I owned this thing.
Luckily, Paul was available right at that moment. so I jumped on the chance to fly down. There were showers in the area and the winds were howling. I ignored my hangover, forgot that I had a dentist appointment that afternoon, and launched for the 15 minute flight to have him take a look. I’m anal retentive when it comes to driving that squawk list to zero!
I was surprised that each individual JPI wire has the purpose printed right on it. CHT #3 was clearly printed on the lead wire, once the bundle was unwrapped. This is quality material.
The only other connections are on the instrument side, and my understanding is that is a production cannon plug. All connections appear good, so we didn’t accomplish anything on the face of it. I definitely did – mind you. This was a necessary step before I talk directly to JPI, assuming the issue continues.
I did learn that some zip ties are able to withstand more heat than others. That was a new concept to me. I also learned more about washer type probes versus blade type probes, and that the engine cylinders already have a plug in the cylinder to accommodate the later. Thanks Gary M for reading my last post and calling me to share what you know. It’s all great stuff and it helps when we work together. Thank you!
There were no obvious connection issues found. Sometimes there are ghosts and gremlins in machines, and just touching them or swearing at them chases them away. Maybe that happened in this case. In any event, we put it all back together as the wind cranked up even more for the ride home.
I made it home in time to hangar the airplane, but not early enough to do it properly. I had to zoom off to my dental appointment and return afterward to finish putting N833DF away.
I’m looking forward to flying again. That might be today, but I’m not sure I know how to fly in less than 40 knot winds. We’ll see. The idea is to put 2 or 3 hours on the engines today, and try to get the CHT issue to repeat itself. When that happens, I’ll look for a warranty replacement of the probe itself.
I am so lucky to have finished this project before all this virus disruption happened. Now I sit here with a clear way to avoid the airlines for all but international travel. It’s been a long hard road, but I’m now poised to take advantage of the results.
Bev and I are planning Florida in July so we can vacation on the surface of the sun, and several other trips with our friends for the balance of the year.
Comments Off on May 12, 2020 – Bumpy CHT inspection
I am ready to go fly again this morning. My last flight was on May 3rd, and you can watch some of that flight in the video clip below. The part I’m focusing on here is where I had flown down the coast and turning northbound as planned. I had just turned out over the water to avoid being low and making noise over populated beach areas when an engine monitor alarm flashed by too quickly to be read. I believe I was at 1500′ when it happened, and had just started the turn east over the water. You can find the segment of interest at around 13 minutes and 30 seconds in the clip.
The flash warning came and went so fast that I missed it, but I knew something had just happened. I remained in the turn, looked for traffic, and then was back inside monitoring that instrument more closely. It didn’t take long before I saw that the CHT#3 on the left engine had shot up from 330 degrees to over 600 degrees in one second!! Then suddenly it was back down to 330 for a few readings, and back up to 500 for a few seconds more!!
My checkbook was quivering at this point. I KNEW out of the gate with a 98% certainty that a temperature movement of this magnitude was nearly impossible without blowing something up. The engines purred smoothly the entire time, and no change in prop synchronization could be heard. This had to be data.
Supporting my theory was the fact that my friend Mike and I had seen one single CHT data point on the same cylinder shoot up and cause an alarm using Mike Busch’s analytical tools on that can be found on his website. We looked at it and discussed it, and agreed that it had to be data. Of course it is my sole investment, but I wanted my friends analysis to make sure I wasn’t blinding myself with wishful thinking.
The same data issue appeared on two subsequent flights, but this last one had several hits. I shortened my plan flight, particularly avoiding a low over the water leg to the NJ coast. I didn’t land short or rush anything, since I remain convinced it is bad data caused by yet a fourth loose connection. On the other hand, I wasn’t taking any chances with further flight until I talked with my A&P.
Getting hold of Paul last week proved a challenge. By the time I did, my wife and I were just leaving for a 3 day trip to visit with friends. We traveled by car, so the airplane wasn’t in play. Paul is the A&P who did the work, and suggested I pull the left nacelle panel and look for a loose connection on the CHT.
The Lycoming IO-320-B1A cylinders are numbered from front to rear, odd numbers on the right, even numbers on the left. That means CHT #3 will be found inboard and rearward on the left engine, so that is the panel I should remove. I found this information in the Lycoming IO-320 operating manual; confirmed it with Mike, and then confirmed it again talking with Paul.
Now all I have to do is figure out what it is that I’m looking for, and where to look for this mysterious loose connection. For some guidance, I downloaded the installation manual for the EDM 760 CHT probe and found this guidance:
5) CYLINDER HEAD TEMPERATURE PROBE (CHT), BAYONET
The Bayonet probe 5050-T has the 3/8-24 boss as part of the probe and is screwed into the base of the cylinder (See fig-2). The bayonet probe has a screwdriver slot to facilitate tightening.
Temperature indicating system with Fuel Flow (that’s me….)
6) SPARK PLUG GASKET CHT PROBE
Most factory installed cylinder head temperature gauges utilize a bayonet or screw-in resistive type probe that occupies one of the bayonet sockets. This probe is not compatible with the thermocouple probes required for the EDM-760.
The spark plug gasket probe, P/N M-113, replaces the standard copper spark plug gasket on one spark plug. The plug chosen, upper or lower, should be the one that provides the best correlation with the other temperature probes.
Due to the spark plug location, the gasket probe may read 25oF higher or lower than the factory probe. The probe is usually placed under the plug that receives the most direct cooling air. After many removals the probe may be annealed for re-use. Heat and quench in water. At additional cost an adapter probe (bayonet) is available that permits the factory CHT probe and a JPI probe to fit the same bayonet location.
I am not sure what I have, but will call Paul and discuss when I’m standing there with the panel off, and have gained some perspective.
If I find something obvious that can be tightened, I’ll go fly. If not, I’ll talk with Paul and maybe stop in on him with the airplane. Failing either of those options, I’ll wait until I talk with him again.
The only pressure point to flying is that I’d like to get to zero squawks again and be done with break-in before I take this airplane and my wife to Florida in July. Let’s just assume Florida will be open and pools will be open where we stay.
Fly safe – I’ll put out a video of my loose connection search later today.
Comments Off on May 11, 2020 – Left Engine CHT#3
The winds are dead calm this morning and the temperature is 29o in Chesapeake City, as you can see from my view out the window. I am so grateful that I put the heaters back in the airplane after the last flight. I had actually thought it would be warm enough in April and had packed them away earlier in the month.
I’m also grateful that I have a place to go and something important to do, now that I’m off of work for 30 days and it is too cold to bike on the trail. Yes, there are folks out there bicycling and jogging everyday, rain or shine, but I just don’t want to be one of them.
The steam fog I can see out of the other window captures the fact that it is both cold and calm, but it won’t be by the time I go flying this morning. Winds are expected to pick up and gust in the 12 to 19 knot range as the sun comes up. It will be worse later in the day, but that has been the experience since I started flying again in mid-February. More of the same.
I’m going flying this morning to gather some data while I perform two types of flying. The initial segment of the flight will be down low at full power, attempting to replicate an earlier flight so that I can evaluate CHTs. As I said in the previous blog, a significant drop in CHTs could indicate that engine break-in has been achieved. I haven’t seen that, and it may be due to the fact that outlying variables had changed. Cowl flaps, fuel flow, and OAT namely.
The second segment will be conducted differently than I had discussed in my previous blog. My understanding of the technical details and discoveries I talked about there haven’t changed, but the strategies for conducting the flight has. My Cirrus flying friend Mike and I spent an hour or so last night on a webex working out the details that will take better care of these engines.
Upon completion of the down low power segment of the flight, I’ll climb to 5,500′ and plan to be near Summit airport in central Delaware. From there I’ll plan a circuit south that will keep me in Dovers airspace, allowing for flight following. My safety pilot bailed on me this morning, so I’ll use Dover as another set of traffic eyes.
The 5500′ altitude affords me less traffic, will hopefully keep me clear of eagles and other birds, and will allow for 65% power in level flight. It will also be cooler to help ensure I can do the lean test with minimal CHT threats on my cylinders.
Here is my updated test plan:
GAMI Lean Test
Fly approximately 30 minutes – replicate the first flight for CHT comparison
- Record Pressure Altitude, OAT, RPM, MP, Oil Pressure, Cowls
- Mixture Full Rich
- Cowl Flaps Open
- 75% power or better – power as high as possible
Perform GAMI Lean Test
- Record Pressure Altitude, OAT, RPM, MP, Oil Pressure, Cowls
- Climb to 5,500’; establish flight following
- Cowl Flaps Open
- Auto-pilot on following route
- Set power 21” MP / 2300 RPM (65%)
- Stabilize 1 minute
- JPI to Manual; prepare to toggle FF to CHT
- Lean one engine to 9.0 GPH
- Stabilize 1 minute
- Monitor CHTs
- Start GTX timer
- Decrement fuel by 0.2 GPH and pause for 10 seconds
- Continue until all 4 cylinder EGTs have peaked
I will download the data and analyze both segments of the flight. The goals will be to determine if I see any CHT drops on the first segment, and then to calculate what the current GAMI spread is by comparing fuel flow to individual EFT peaks. It will be interesting to see what the data reveals.
This is what the long hand form looks like for determining GAMI spread.
I’m going flying and looking forward to it!
Comments Off on Apr 19, 2020 – Going Flying Today
One thing I have noticed in perusing the JPI Engine data is that the left engine cylinder #4 has been running significantly hotter than any other. That could be due to the break-in not being completed, or it may indicate the need to fine tune the new GAMI injectors to a tighter fuel flow spread.Of course, this could all be entirely normal, or it could be something else I haven’t yet considered.
In order to evaluate each engines GAMI spread, and thus eliminate injectors from further evaluation in the case of the hot LC4, I will be conducting a GAMI Lean Test on the airplane. Since this involves determining peak EGTs for each engine, and thus successively leaning each one, care must be taken so has not to abuse the cylinders as the data is gathered. This is where the GAMI technique is combined with the Red Fin concept and LOP leaning techniques to keep me safe.
I am relying on several resources to help me prepare for this upcoming flight. Mike B, (not Busch) regularly flies Cirrus aircraft and introduced me to LOP and the Red Fin. He is my other set of eyes on this data and my understanding of it. Mike Busch is the author of ‘Mike Busch on Engines’, which has been my source for understanding the leaning process of non-turbocharged, fuel injected engines. He has a video tutorial on the break-in process which I’ve studied more than once. Finally, the GAMI fuel injector website has information on conducting the test and the company has offered to analyze the results once complete.
Background: N833DF has ‘new’ engines, and I’m uncertain as to whether the break-in process is complete or not. Per the collective wisdom, stabilized oil consumption and/or a clear drop in CHT per cylinder would indicate that break-in has occurred. I didn’t believe that would be obvious when I read about it, and I certainly haven’t seen indications of that in the data. I am not putting much faith in my ability to see a clear delineation of either variable with this approach.
Penn Yan overhauled these engines and says that engine break-in can take as little as 10 hours or as long as 100 hours. They tell you that stabilization of oil consumption is the key to knowing when your engine is broken in. They don’t mention CHTs at all. They’d like to see 75% power the entire time, and no touch and goes for first 30 hours. This is actionable advice.
Mike Busch says to watch CHT for a clear drop of 20-40o that would indicate break-in has occurred? I doubted from the outset that I’d see an indication like this, and I haven’t. Too many variables and too simplistic an approach. In his video on engine break-in, Busch says to allow up to 440o during the break-in for Lycoming engines. Note that he also states in one document that your should operate Lycoming engines up to 380o, and in another up to 420o normally. That is a considerable range and difficult for an engineer’s mind to apply. Still another reference calls for 400o as the maximum CHT.
Detecting CHT drops: I ran the engines hard the first 10 hours, allowing LC4 to get to as high as 430o. After the 10 hours, I limited myself to 75% power and 400o on any cylinder on the assumption that break-in may have occurred and I’m not aware of it. The weather and I have been inconsistent, so the CHT drop may have been masked. In retrospect, it would have been good to have recorded Pressure Altitude, MP, OAT, RPM, and Cowl Position for each flight. I’ll do that on subsequent flights if I can manage it single handed.
I’ll start off the GAMI test flight with a period of time at full power; full rich, cowls open at 2000′. I’ll compare that with the first flight on 2/19/2020 with the same parameters at 2o OAT and see if I can detect any CHT drops between the two.
Detecting oil consumption stabilization: How the hell would I be able to detect that already? I put 1 quart in during the first 10 hours, which is no surprise given that I was running around balls-to-the-wall the entire time.The general advice is to precisely position the aircraft in the same spot on the hangar each time, and measure the oil consumption each day. Measure with a micrometer, mark with a chalk line, and cut it with an axe. This is an approach that is just silly, in my mind. No way you can be accurate. I’ll measure it in 10 hour increments instead, thought I’ll obviously check it every flight. Pointless exercise for now.
That means I have no idea if these engines are through the break-in process or not. The engines are running well and developing excellent power. Fuel consumption is up, but my flying pattern is completely different. Nothing to see here, so let’s focus on LC4 being at a high CHT and go find out what our GAMI injectors are doing.
Current operating philosophy is to continue to use only high power settings (except for the short period I’ll run this test); keep all CHTs under 400o; cowl flaps open or closed based on CHT; and lean no further than 10 GPH while at full power. I do not know where peak EGT is at 75% power. Minimize low power operations. The 10 GPH leaning may be changed based on what I learn during the test.
Leaning is a very good thing, unless you do it incorrectly. Then it can be bad. Really bad. I’ll be revisiting this subject once I’m sure break-in is completed, and begin to operate LOP and ROP.
Mike Busch (paraphrased): High CHTs often indicate that the engine is under excessive stress, which is why it’s so important to limit CHTs to a tolerable value (no more than 400°F for Continentals and 420°F for Lycomings). High EGTs do not represent a threat to cylinder longevity the way high CHTs do. Therefore, limiting EGTs in an attempt to be “kind to the engine” is simply misguided.
EGTs are expected to be different (JPI DIFF measurement). It is not uncommon for well-balanced fuel injected engines to exhibit EGT spreads of 100°F. In fact, EGT spreads are usually smallest near or just rich of peak EGT (the worst place to operate the engine), and often significantly greater at leaner or richer mixtures (that are much kinder to the engine).
The mark of a well-balanced engine is not a small EGT spread (“DIFF”), but rather a small “GAMI spread”—defined as the difference in fuel flows at which the various cylinders reach peak EGT. Ideally, we would like to see this spread be no more than about 0.5 GPH (or 3 PPH). Experience shows that if the GAMI spread is much more than that, the engine is unlikely to run smoothly with LOP mixtures.
There is no such thing as a maximum EGT limit or red-line, and trying to keep absolute EGTs below some particular value—or even worse, leaning to a particular absolute EGT value—is simply wrongheaded.
50°F ROP is almost precisely the WORST possible mixture setting from the standpoint of engine longevity. The maximum cylinder head temperature (CHT) and peak internal cylinder pressure (ICP) occurs almost precisely at 50°F ROP. The hottest, most stressful mixture is about 50°F ROP, and mixtures that are richer OR leaner are better for the engine.
At 75% cruise power, you want to stay well away from that worst-case mixture setting, either by operating at least 100°F ROP (preferably richer) or at least 20°F LOP (preferably leaner), take your pick.
Mike Busch’s leaning technique – paraphrased
- Generally, cruise LOP to be cooler, cleaner, cheaper, greener
- Don’t use EGT as a leaning reference for cruise flight. Absolute EGT values are meaningless. Determining peak EGT by leaning very slowly puts the engine in the area of maximum stress and ICP routinely. This is a Lean-Find approach.
- Do I want to go fast (i.e., achieve maximum airspeed) or do I want to go far (i.e., achieve minimum fuel consumption)?
- For modern airplanes like the Cessna TTx or Cirrus SR22 or Diamond DA40 with their superior engine cooling systems, those target values should be reduced by about 20°F.
- In cold OATs (below ISA), the CHT targets should also be lowered a bit.
- Fast: Lean so that the CHT of my hottest-running cylinder does not exceed 400°F for Lycomings. Does this imply that you can do this ROP without knowing where you are in terms of peak EGT???
- Far:Conversely, if the hottest CHT is lower than the target value, I can gain a bit more fuel economy by leaning a bit more (if ROP) or a bit more speed by richening a bit more (if LOP). Best economy occurs at Peak EGT. You’ll fly slower but further.
The Red Fin
Defines an area or zone of operation where we should not be. Note that the GAMI Lean Test calls for 65% power being used, and that is the very tip of the dark (danger) fin on the right. They recommend less power if the CHTs get up close to 400o as well. The GAMI test will determine where peak EGT is for every cylinder at 65% power. This graph relies on the first cylinder in each engine to peak.
[Again – extracting from Mike’s book] Busch recommends NOT using the “lean-find mode” of your engine monitor when doing this [leaning], because this requires you to lean very slowly to locate peak EGT. That results in spending a considerable amount time inside the red fin (and the dreaded purple zone), which is exactly what you don’t want to do.
When we reach top-of-climb, level off, and commence the cruise phase of the flight, we perform a “big mixture pull” (BMP) to transition from ROP to LOP. This should be done quickly to minimize the amount of time spent inside the red fin (and especially the ultra-abusive purple zone). About 2 or 3 seconds is about right for the BMP. Note that we lose a bit of power as we transition from ROP to LOP; that’s normal and expected, and will be reflected by a small loss of airspeed.
One question for Mike Busch – you say you don’t have any idea how far from Peak EGT you operate LOP, but at the same time, recommend at least 20o LOP for us. I’d say you have two methods for LOP. The first would be to manage CHT on the peak cylinder and assume that will give you better than 20o LOP. The second would be to precisely measure peak EGT from the lean side, and choose something greater (leaner) than 20o LOP. I found the answer in his book…..
Busch continues: If you feel compelled to locate peak EGT, it’s much better to perform a quick BMP to get into the LOP zone below the fin, and then slowly richen to locate peak EGT from the lean side. Personally, I don’t care about locating peak EGT, so I skip this step altogether. I just do a quick BMP to a known-safe LOP fuel flow—or until I hear and feel a small power loss that tells me I’m safely LOP below the fin—and then fine-tune the mixture using either CHT or my fuel totalizer as a primary reference.
Profile for the GAMI test
- Fly a period of time replicating first flight / CHT comparison
- Mixture Full Rich
- Cowl Flaps Open
- 75% power or better – high as possible
- Record Pressure Altitude, OAT, RPM, MP
- Pick up Safety pilot 33N if available
- Brief safety pilot duties
- Safety information
- Purpose of the flight today: Develop lean test data for GAMI engineers
- Electro-air ignitors
- GAMI injectors
- Handle radio as necessary
- Monitor legs page / planned route
- Navigate clear of airspace in pre-defined pattern
- Watch for traffic
- Monitor auto-pilot
- Maintain directional during repeated asymmetric thrust scenarios
- Don’t use rudder trim due to continuous change expected
- Be prepared for engine failure / unexpected power loss
- Climb to 3,500’ and check one engine at a time
- Set power 22.5” MP / 2300 RPM (65%)
- Record Pressure Altitude, OAT, RPM, MP, Oil Pressure
- Auto-pilot on following route
- JPI: Set FF/All/EGT switch to EGT for engine only data
- JPI: Set MANUAL Indexing and cycle to Cylinder #4, the highest CHT
- JPI: Still in MANUAL, Set FF/All/EGT switch to FF. Cycle through to display FF.
- This will allow toggling back and forth to check CHT #4 as necessary, and fuel flow in progress
- Lean the right engine to roughness (big pull) and richen to smooth operation.
- Move mixture such that it takes 2-3 secs to accomplish
- Note Fuel Flow
- Set FF/All/EGT switch back to EGT; monitor CHT
- Monitor CHTs and wait one minute to stabilize
- Use JPI toggle switch to check on CHT #4 either engine (hottest), and then back to Fuel Flow
- Slowly enrichen the mixture at 0.2 GPH increments (to allow data capture)
- Toggle between CHT #4 below 400o increasing Fuel Flow at 0.2 GPH increments.
- CHT shouldn’t be an issue doing this from the lean side and at reduced power (65%), but I’ll stop the test and reduce power if it is. Note that the Red Fin as it’s tip at 65%.
- Monitor all 4 EGTs on the bar graph until seeing them all moving down
- Restore mixture to 10 GPH
Comments Off on Apr 17, 2020 – GAMI Lean Test
N833DF may not be the best Twin Comanche out there, but I can assure you it is the most expensive
This quote is something I came across in one of the aviation magazines I subscribe to, so I stole it. It is certainly true for me, and the joy I have flying this thing keeps me from crying 😉
Cross-country flight: Saturday, April 11th was supposed to be windy with gusts up north, but calm winds down near my destination, southwest of Norfolk, VA. Lately I’ve been flying in whatever wind I end up with so that I can get back in the groove again. All of my landings have been satisfying thus far, except the last one. I happened to notice the wind finally dropped to maybe 7 knots off the right wing, so I opted for my first full flap landing in awhile.
What I didn’t do was slow down enough. I’ve been battling high and gusting winds all along, so I’ve been adding airspeed and using little or no flaps. The result of coming in with full flaps and a higher airspeed was predictable. She didn’t want to land and I bounced it a few times.
For today’s flight I planned the flight south at 4,000′ while keeping the power up to at least 75% (24 squared). I’d either land at KPVG and taxi back to pick up my next clearance, or do a low approach and pick up that clearance in the air. That would give me some practice with what I’ll call IFR administrative duties. Shaking off the rust and getting back to normal again.
I have three action cameras now, 2 Heros & 1 cheap ActionCam. Rarely have I taken the time to use more than one of these cameras on any one flight. My interest in using multiple cameras at once changed when I watched a Bonanza pilot blog where the pilot used multiple cameras and perspectives to great effect. He set a high bar, in my opinion, that I acknowledge will be difficult for me to reach with the time I’m willing to invest. I am currently more interested in spooling back up my PA30 IFR skills than I am in improving my video skills. Maybe I can do both – we’ll see.
Engine Management includes continued break-in procedures. During this flight I kept the power up to 24 squared (75%) but did begin to lean from full rich. I leaned both sides initially to 10 gph and watched the CHTs. I acknowledge that I paid little attention the EGTs since this process started, since the entire focus has been full rich and cowl flaps open anyway. Now that I’m leaning and working the cowl flaps toward closed in cruise, I need to re-read Mike Busch and other sources to plan my leaning process going forward.
It seems to me that the right engine is fully broken in, based on CHT performance, and all that is left is to verify stabilized oil consumption. The left engine #4 cylinder has been running 40 degrees hotter than the same cylinder on the right, and I’ve been watching that as my limiting factor all along. Toward the end of the flight today, I did see that CHT drop to 30 degrees hotter. I think that one is finally breaking in. Can’t wait to see how it looks on the next flight.
You can see my one camera video on YouTube for this latest flight, along with many other videos included in my channel. Subscribe if you’d like to stay in touch and have something to watch.
My next flight will be in a different direction, possibly north. I’ll determine the range to ensure I have enough fuel to get home if the FBO happens to be closed suddenly. I’ll most likely install permanent sticky mounts for the GoPro on my sundeck, and put those other mounts away. We’ll see if I can ramp up to 2 cameras for the next flight, and also include battery power for the Hero8.
Comments Off on Apr 11, 2020 – Cross Country Run
Beautiful weather today and I took full advantage of it. Bev and I cleaned the dust out of our downstairs living area and polished the furniture. I turned on the electrostatic air filter and fan, and verified all the heating systems were turned off for the season. The washing machine we had repaired hummed constantly in the background, and I’m still feeling a degree of self-satisfaction with how well that went.
Then it was out on the trail with my Cannondale bicycle. I hadn’t really exercised much (at all) and had put on some weight over the last six months. I’ll blame it on winter weather, work stress, excessive travel, and keeping odd hours to attain all of my instructor qualifications on the G280. The only way to fight back on the weight issue when you are in your sixties is to add back the exercise. Eating less and drinking less beer when you live on the canal is a last resort I’m hoping to avoid.
Gone are the days when I could ramp up quickly and not hurt anything, so I vowed to start out easy and build up to riding the trail to the Grain restaurant and beyond. Out on my first ride, I was truly surprised how quickly I was moving along. Riding along was feeling easy as I reached the first big hill and down-shifted for the climb. At the top with not much effort, I seriously considered continuing on toward the next big hill and Grain H2O. Then I remembered the wind. The ride east had been like riding in no wind, even though I was moving along at over 10mph. That meant the wind was at my back, and would be hitting me in the face all the way home. I had made the mistake of under-estimating wind effects last year, and ended riding all the way to Delaware City thinking I was a rock star. The ride home had been arduous at best, and included a minor crash and a new understanding of wind effects on bicycling.
The decision was make to return home, ensuring that I ease into the effort again and not over exert on the first run. It was the right decision, as the effects of a headwind became apparent along the water. I made it back with a reasonable effort, very much enjoying the experience. Back into the ride, the water, and the sunshine.
Now that the housework and exercise were completed, it was time to pull out the Harley and take a ride to the airport. That is the definition of a very good day; getting a few things done at home and then riding a motorcycle to get the airplane out.
April 2nd was my 62nd birthday, and I celebrated it by flying my airplane home after it’s 10 hour mineral oil change. The filters were replaced and new 100W mineral oil was put in for the next 30 hours of operation. Bolts were tightened and one more inspection on the mounts and new accessories was completed. Everything looked solid, and I’m told the airplane sounds simply bad-ass. This was also the day that I paid the final bill on this project, which came out reasonably close to expectations, I’m happy to say. Thank God I started this project when I did, and that it ended at this point. I’d have been a bit more nervous if the project had just begun, and I’m certain there would have been countless months of delay added in there. I dodged a bullet.
When I dropped the airplane off the week prior, there were three known issues. Only one of these, the right alternator, would be addressed during this visit.
The vacuum A/I had been slow to erect on three occasions now. That will need to be overhauled before I begin doing instrument work with the airplane. Normal maintenance and I’m not worried about it. I need to hold off on it though, as I could send it out and not get it back until the virus clears. Let’s wait.
The fuel gauge in the airplane is pressure based. It read 8 gph on the left side during the first takeoff back in February. The right side was reading 12 gph correctly at the same time, which agreed with the EDM 760. On a subsequent flight, the pressure on the left side dropped all the way to zero and stayed there. The distraction caused by the left side flow flow (pressure) was the reason I forgot to raise the gear on that first takeoff!
Paul knew I had issues and blew out the line to the gauge while he was inspecting things. That did the trick, and I’ve been seeing accurate readings for the last few flights. Consider that gauge off of my squawk list. Good news!
We had intended to repair or replace the right alternator and/or voltage regulator during this visit. Turns out a loose connection was the culprit that caused the voltage spike. It is now working reliably in conjunction with the left side. No more voltage spikes, and no need to replace a voltage regulator and/or alternator. More Good News! I like where this is going.
That means the only squawk I now have is the vacuum A/I, which I’ll take care of after the pandemic restrictions allow people to return to work. Probably at the next oil change.
Frank’s Work Update: I am working through initial classroom instruction with a fellow instructor in the G280. It is just he and I and one other employee in the room these last few weeks. He is really doing well and doesn’t need me there except to have an audience to practice on. It has not been boring at all, and I’ve learned quite a bit more about the airplane while working through it with him. We are refining talking points together.
My work has put out a voluntary leave program during this pandemic. I’ve volunteered for it, and fully expect to be off from mid-April through mid-May. The leave can be extended monthly by mutual agreement, so it will be interesting to see where this goes. I see that as practice for adjusting to social security and not working.
This could be a trial run for me to determine if I can keep myself occupied without working. I’ll also be able to see if I’ll have an adequate cash flow to fuel my toys while not working. It has me thinking about what’s next.
Comments Off on Apr 5, 2020 – Satisfying Developments