Milestones

[Nemesis]

There are only but a few real milestones in aviation. First solo, a freshly minted PPL or new instrument rating, descending that first time into the muck on an approach - without an instructor on board, searching for and ultimately buying a first airplane, the first time that a primary instrument goes haywire or you loose vacuum - hopefully in VFR conditions, who can remember those first 500 mile trips - manageing the airplane, navigating, landing at a strange airport, etc. After more than a year of ownership, the places that I normally go, the peculiarities of this airplane, my weather go/no go decisions, basically my familiarity, many things have started to become routine or commonplace. I am always fighting to be sure that they do not manifest as complacency. One new thing recently was the annual inspection after my first full year of ownership.

The machine: 1980 M20K 231, TSIO-360-LB

I know that many or most on these lists or forums have lots of experience with inspections but I have very little. Hey, that experience is why I lurk on the email lists and forums. I did not fear my inspection. I know the condition of my machine and if there were any doubt in my mind I sure as hell would not climb into it. But then there is always the unexpected. So, for those without all of the experience in the world and perhaps even a tip or two for those guru types, I offer the following. (Crap, two paragraphs just as introduction?)

I set off a week ago last Monday to see Jason in MN and renew our friendship. My goals were - annual inspection, Merlyn wastegate, the upgraded alternate intake air system for a 231 (who knows why the original owner did not get the free or discounted kit when offered but they didn't), new battery, change a tire that was flat spotted before I owned the plane, and balanced fuel injectors. In the last couple of months I had acquired all of the parts that I needed. I planned on swapping two injectors but if that did not work I ordered GAMIs anyway. Jason had a new Concorde RG-35AXC for me and tire and tube. He also ordered the Merlyn WG kit and a new exhaust elbow in case my old one would not work or come apart. I called a bunch of salvage places to find the alt air box. Finally Wentworth called me back and sent one over and for only $145 too, nice. With my parts package complete, I only had to wait for the appointment.

As soon as I landed in Benson, we backed the airplane into the hanger and removed the cowl. While Jason checked compressions on the warm engine, I commenced removal of the inspection panels that he wanted off and then started to clean up the belly. How could it be that dirty after only two months? Well, I did a lot of flying during the holidays and since. Cleaning the belly is a ton easier with a decent creeper and a good floor. As it turned out, the air box that Wentworth sent was not the right one even though the part number they wrote on it was correct. They probably just copied the number from my email. Compared to the parts manual it sure looked good to me. Fortunately, a 10 minute phone call later and the correct part was on it's way for Tuesday delivery. After lunch, I continued cleaning and he got down to the nitty gritty of the inspection and lubrication. I was getting tired from the traveling and working by about 4pm and Jason has a van available for customer use. I grabbed the van and went to the hotel. That was enough for me on Monday.

When I showed up from the hotel on Tuesday morning at about 9am, Jason had already put most of the inspection panels back on. He must have kept working well past 5pm the night before. Somewhere around noon he was putting the belly panels back together and for the most part the inspection was finished. The new tire was on the right main as well. All told and in addition to lubrication, Jason had cleaned up a sticky micro-switch on the stall warning, tightened a couple of things on the nose gear, replaced the brake linings, and made note of the correctly installed filler plate in the tail. That was it. All of the things that we were careful to inspect and repair at pre-purchase / 1st annual paid off and as I expected most everything was tip top. If I were there only for the inspection, I would have been home on Tuesday afternoon.

It was getting to be about 1pm on Tuesday and normally UPS shows up about noon. Jason called Wentworth to be sure they had sent out the air box. What! They didn't? The guy said that the Mooney application calls for slightly different part numbers and he was not sure what he had. Thanks that he did not even bother to call. After reconfirming what we wanted he promised that it would be in UPS for Wednesday delivery. Ok. Change out the battery. Simple, and there would be part of the afternoon for the Merlyn wastegate. Jason even fit in changing out a prop on an F model for a fly-in customer from Flying Cloud.

The exhaust came apart easy enough, even the bypass elbow where the WG goes. My original has course threads and the new WG has fine threads. Good thing that we ordered the new elbow. The first trial fitting of the elbow / exhaust pipe / turbo flange shows giant gaps as the three parts don't fit together at all. After some more trying, twisting, pushing, and pulling, we are getting nowhere. That elbow just does not fit worth a crap. It won't slip over the pipe on top, and it won't slip into the pipe on the bottom. Everything is nice and clean and the original fits perfectly. After a couple of phone calls to Merlyn and sending pictures, an engineer at Merlyn says that the new elbow that they sent does appear to be of poor quality. But the only solution that we could get out of him was to send in both the new and old elbows and he would send back one that would work. For some reason he would not send out another new one of better quality. Very disappointing for a $3000 kit. The wastegate controller itself seems to be very good, but the poor customer service together with the admittedly substandard elbow leaves a bitter taste regarding that company. Jason's experience tells him that we should just modify what we have rather than wait a week or more for Merlyn to come through. So, we nip the very end off of part of the elbow and also off of one pipe on the exhaust. That gets it much closer but not perfect. I spent two hours in the hotel that night with emery cloth making each of the parts fit perfectly dry. There was no need to pay Jason to sit there hand fitting those parts when I could do it myself.

I got up earlier on Wednesday because I had all the parts that we needed at the hotel. 15 minutes after I got there and with a little anti-seize compound, and the exhaust is back together with a perfect fit; but it took 5 or 6 hours of hand fitting to get that bypass elbow to work. By noon the MP lines were in and the #2 and #5 injectors were swapped - my most rich and most lean. We slapped the cowl back on for a quick test flight to see if swapping the injectors would help balance them any better. Plus, the air box should show up any time. It looks like even if the GAMIs have to be installed as well as the air box, I should have no problem going home on Thursday. I started to do a run up per the Merlyn instructions and noticed that the charge amps were flickering between zero and about mid scale positive charge. Jason jumped in and adjusted the voltage regulator a bit, maybe something with the new battery I guess. The new WG worked perfectly by the Merlyn instructions so the test flight was on. Swapping the injectors did absolutely nothing. It was as if nothing was changed at all. My CHTs were identical to before and the lean test gave exactly the same results, #5 lean and #2 rich, and a rough running engine anywhere close to LOP.

Now it is 1pm and no UPS. Another call to Wentworth confirms that they screwed us over again. This time the guy says that he looked up the old invoice from when they sent the part to me a couple of months back and it had the identical part number so he did not send out anything. Thanks once again for not calling. Does this guy not understand english? The part we have is wrong, the picture of the part that you sent is correct, send the damn thing. Another promise to send, time wasted, together with a few choice and colorful words that I will not repeat here. It is a shame that for salvage parts, there is really only one player that has a good inventory. Wentworth is not high on my list of companies to deal with. So, lunch then disassemble the air intake in preparation for the ever elusive alt air box, install the GAMI injectors, and that pretty much kills the day. We didn't plan on testing the new injectors. Either they will work as advertised or maybe I will have to change out one or two in the future after some cruise testing. Either way I am not going to be making any more injector changes this trip.

Thursday morning and I go and have a good breakfast at this little diner where all of the farmers hang out. Every 'farmer' diner that I have been in always has good breakfast, much better than the ' continental' at the hotel. When I show up at 8:30, Jason is driving up at the same time. He always takes his kids to school at around 8am. Inside the shop the new alternate air system is almost fully installed. It turns out that he had another airplane in a different hanger that he scavenged the box from. He had enough confidence that he would eventually get the one from Wentworth so he took the one from the other airplane. We both left at the same time the night before so he must have been at work at 5am to get all of that work done and then return home to take his kids to school. About the only thing left to do was complete the wiring to a micro-switch on the new box. It took a little while to do that, then he was off working to complete the paperwork. I loaded up the airplane for the trip home. Jason started up the airplane to taxi to the fuel pump while I finished putting the paperwork together in my books. After lunch I would launch for Denver. While he was running up and taxing the airplane, the amp meter was flickering again. We ate at the diner and talked over the strange charging condition.

 After lunch the weather was turning very cold but still VFR, just a very cold air mass moving into the area with very little cloudiness associated. While I handled the controls, Jason was on his back trying once again to adjust the voltage regulator. When the voltage was turned down to 13 or 13.1 volts, the flickering stopped. As soon as the voltage was adjusted higher, the VR would go into cutoff again. I guess the new battery was too much for the old VR. Luckily he had another available. 10 minutes later with the new VR the same condition existed. The voltage could be adjusted a bit higher, maybe 13.3 or 13.4, but any higher and it would cut out again. Something was just not right.

Several calls were put in to different companies including Concorde. Concorde was the first to call back. The guy on the phone sounded a bit older and he identified himself as a company engineer. I did not get his name. After the condition was explained, aircraft type, VR, new Concorde RG battery, he immediately went into a story of how many times he has come across the very same problem. He said that after many years and many such cases, he does not know the exact reason, and the reasons may vary by airplane, age, connection corrosion, alternator, and other installations, but the old style mechanical VRs (with points) do not behave well with the sealed batteries. He said get a Zeftronics (solid state) and that would solve the problem. The charging voltage could have been left at that low setting and I could have probably gone to Denver and had the new VR installed later, but with all of these type decisions in aviation, I decided that the best thing to do was to stay put for one more night if a VR could be sent overnight. Then I would have a definitive solution before leaving.

UPS does their sorting for the area in Morris MN about 20 miles NW. Jason offered to go to Morris early on Friday morning and pick up the new Zeftronics regulator at the UPS office rather than wait for the truck at noon. I flew the airplane over to Morris and he put in the VR there on the ramp. 5 minutes to install, a short run up, the flickering on the amp meter was gone, and the voltage and charging current were both perfect. There are no adjustments on the Zeftronics. I shook Jason's hand with many thanks, I was on my way back to Denver.

I remember seeing many threads about charging problems over the last couple of years and how much time and money was spent on those problems. I was almost in the same trap. We could have changed alternators, cleaned every connection on the high amp lines and regulator lines, changed breakers, and maybe even gone as far as ordering more batteries or changing the alternator drive coupling, and all would have been worthless and expensive. That 5 minute conversation with the guy at Concorde saved days of time and countless dollars. Certainly all of those other things have value, clean connections, alternator in good condition, that crappy drive coupling on the TSIO-360-LB model engines, good battery, but high on my list of advice for the group is to get rid of the old style voltage regulators especially when combined with a newer style sealed battery.

What I found on the trip back to Denver was that throttle response with the new automatic wastegate is more crisp. There are also less throttle adjustments necessary to keep the MP at the value I set. I wish that I had a turbo RPM gauge to see what the difference really is. My CDT is about mid-scale while in climb but I have never seen it much hotter than that anyway.

As far as the GAMI injectors go, I can run LOP right now down to about 8 GPH with the engine still pretty smooth. That is down in the 50% power range. Of course, that power level is not why I have a Mooney. I was able to get to about 65% or 68% LOP but after that, my TIT goes over the 1650dF mark. So, TIT is going to be my limiting factor. I would sure like to find a way to get back to about 75% and still be perhaps 40dF LOP or some comfortable margin. I will keep experimenting as well as make some inquiries about how I might be able to do that. The high TIT occurred with about 32" or 33" MP, 2500 RPM, about 10.5 GPH and at 16,500 ft. I also did a couple of GAMI spread tests at 65% power. One showed a spread of about 1.0 GPH and another showed about 0.6 GPH. I do not know which is correct and do not consider these results truly valid. I need to do several more tests and see if I can get some repeatable results. All I know for sure is that the engine is pretty smooth LOP. Perhaps it can be even better.

As I said above, #5 has always been my leanest as well as hottest cylinder. Normally ROP at 75% to 78% power, it runs about 365dF to 368dF consistently. Even though it was the leanest cylinder, it partly did not make sense that it was hot because it is also in the front and gets the first blast of cooling air. What does make sense is that it is my cylinder with the lowest compression since it is the warmest. Together with the voltage regulator business, the most significant outcome from this whole process is that the combination of the Merlyn wastegate and GAMI injectors have made my cylinder temperatures drop and more consistent. Before, my temps were out of place for where the cylinders are in the cooling chain. In other words, the front pair with the most direct cooling air were not the coolest, the middle pair were not necessarily slightly warmer, and the rear pair were not necessarily warmer than the middle. Again at the 75% to 78% range ROP, my front cylinders are now running about 305dF and within 5dF of each other; that is a drop of 60dF for #5. My middle pair of cylinders are at 315dF and within 5dF of each other, and my rear pair of cylinders are about 335dF and within 10dF of each other. How consistent is that? With #5 now running much cooler on this 1300 hour engine, maybe these changes are just what was needed to get this engine to TBO or beyond. If that is the case, this investment will pay out big in the next few years.

There is one other thing that qualifies as significant outcome. Jason Doscher, Jed-Aire Aviation, Benson MN, is a fine mechanic and everything that he did last week only confirms for me that he is more than fair and will keep my ass safe in the air.

I don't know why I like writing these diatribes. I don't really contribute very often to the lists and forums but I hope these writings have some info that will help other owners/operators/lurkers.

Dave
1980 M20K 231
N231NF KFTG and KCXL

[carusoam]

Dave,

Nicely written.  I feel like I have been properly schooled in the proper techniques of operating a turbo engine and working with a good mechanic.

Best regards,

-a-