News from the engine shop

It's been a long time since I wanted to write this update and the Christmas holidays is perfect for it : )

The main symptom my engine had was typical: corroded lifters and cam lobes. Two lifters were definitely not airworthy:

The source of the metal found in the filter was mainly from the lifters. When reading this article about lifter destruction stages, it is pretty evident that these were in stage #3 and had to be replaced.

Since the cam was not in good shape neither, it also had to be changed. Took the opportunity to switch to a high performance cam (different lobe shapes that modify the lift and duration to optimize valve timing and increases combustion efficiency)

This engine only has 500h since new. The cylinders were inspected at the shop and were found in good condition so it was worth taking this opportunity to proceed with porting/polishing of their induction and exhaust tracts as well as carry out a flow balancing on them. This allows a higher volume, to flow with greater efficiency to and from the combustion chamber, hence producing more power.

While the cylinders were getting ported, the crankcase and oil sump got completely cleaned and painted:

The reassembly was also initiated:

Once the cylinders were back, they went for honing, but this revealed an unpleasant surprise: the inside of the cylinder walls were also affected by corrosion:

The solution for this was to oversize the cylinders by 0.010". This howevers means new, oversized pistons and rings. Here's a shot with the cylinders painted and the new pistons followed by pictures of the final assembly:

Once the final assembly was done, the engine got installed on a test bench with a dyno. They ran it for a few hours and checked twice the oil filter for metal. Thank God nothing was found this time! Testing on site is is nice because the break-in of the engine is actually done at the shop. Dyno results were also interesting: with the high performance cam and ported cylinders, the engine produces about 10% more power at 2700 rpm.

The engine is still in the shop of Aerorecip in Winnipeg; it will be shipped right after the new year! Been working on a new firewall in the meantime which is going to be the topic of my next post.

Happy holidays to all of you my readers! I hope 2018 will be full of happiness and interesting projects for you!

Metal in the oil filter

Yes, you read the title right.

In August, shortly after the return from the Green Mountain Aerobatic Contest in Springfield Vermont, I made an oil change since my oil was 4 months old (per Lycoming Service Bulletin No. 480). The engine total time since new was a little more than 500 hours. The oil had 25 hours on it and the oil filter 40 hours.

I have a B&C spin-on filter adapter that allows me to use a 48108 paper filter. I like it since it provides better filtering and allows to change oil every 50 hours instead of 25 hours when using a screen filter (especially useful in summer when flying a lot).

In order to inspect my old filter, I used the "blue rag" technique recommended by this EAA video. When cutting the filter open, I didn't see any big particles with naked eye. However, when I collected all the content of the filter together, I found about 1/8th teaspoon of ferrous metal powder:

Following this finding, I wanted to know what are the typical recommendations for this quantity of metal. Lycoming Service Instruction 1492 has info on recommended actions when finding metal in the oil filter. When reading this SI, I concluded category 8 d. was the closest to my situation:

"As in step b., but larger amount, such as 45-60 small pieces – change oil filter and clean suction
screen, drain oil, and refill. Run engine on ground for 20-30 minutes. Inspect oil filter suction
screen. If clean, fly aircraft for 1 to 2 hours and again inspect oil filter/suction screen. If clean,
inspect oil filter/suction screen after 10 hours of engine operation."

The step b. in question mentions:

"10 to 20 small (1/16 inch diameter or less) pieces of shiny flake-like, nonmagnetic, or 10 or
fewer short hair-like pieces of magnetic material"

The particles were all magnetic and way smaller than 1/16". Stricly speaking, they were not "hair like", but I didn't find a description in this service instruction that fitted better my situation. The generic recommendation from Lycoming is therefore to continue flying "on condition".

The following factors specific to my situation were also worth consideration:

1. The engine was manufactured in 1979 and has never been opened since new. If it had flown consistently 1 hour every month since new, corrosion wouldn't be too much of a worry, but obviously it is not the case. Lycoming cams and lifters are know to be subject to corrosion if not operating for extended periods of time.
2. The situation will not improve by itself. It can only get worse. More particles like this means more chances of getting into other parts of the engine and making more damage.
3. This engine is in a Pitts. Lycoming's recommendation applies also on a Cessna 152, but I think nobody would argue that the severity level of an engine failure on a Pitts is more hazardous.

...so in light of all the above factors and recommendations...

Yes, I know. The bullet is getting pretty chewed up, but here I am. Season is over after only 15 hours of flying : ( It was a very intense 15h though and I enjoyed every second of it. I'm already anxious to put a nice, clean engine back in and go fly next season.

Thanks to Mathieu who helped in crating up the engine. Big thanks also to François Marquis, Kevin Horton, Mike Busch and JP Ouellette who all were of great help in gathering the pieces of the puzzle to make my decision.

Here's a shot of the engine just before getting shipped to Aerorecip in Winnipeg:

Next post will be on the findings from the shop... Stay tuned!

First run up!

The aircraft was fueled, all parts were on the airplane except the cowl. Here are the checks I made in preparation for the first engine run:

• Made sure all screws were fully secured on all panels; this thing blows
• Fuel boost pump check and wobble pump check (using fuel return line w/ purge valve)
•  The noise from both the boost pump and wobble pump was suggesting air was in the system. Took several wobble pump strokes until all cavities were filled with fuel, with no variation in noise.
• Found a small leak at the wobble pump outlet. Tightened fitting a little more and it stopped.
• Injector check: #2 cylinder was getting slightly more fuel than the others. Ordered a smaller retristrictor from Airflow Performance, but left it as is for the first run.
• Attached the oil cooler with lockwire to make sure it doesn't flop around.
• Plugged battery overnight before
• Overall inspection
• Briefed procedure in case of fire or other major engine/prop issue

The plan was then to:

• Roll the airplane outside and attach it to the car (brakes should work, but I haven't fully tested them yet)
• Put wheel chocks in
• Bring a fire extinguisher not too far
• Make a first run, checking:
• oil pressure/temp
• proper functioning of the throttle/mixture cables
• mag drop
• External inspection for leaks
• Make subsequent adjustments to idle mixture (which tipically requires many starts/stops) and check proper functioning fot he new T-30 tachometer

Sticking to the above plan worked well. The engine started quite well on the first attempt; see video below. I got great help from my dad and my friend Luc to prepare the setup and supervise the first engine run. Big thanks to you both!

We identified one oil line fitting that needed to be tightened a little more, which I did. There was also a fuel drain valve below the fuselage that was slightly leaking, but other than that, I was very pleased with the result of the first run. The new tachometer worked also very well (I used the 47k ohm resistors). We did make a few more runs to adjust the idle mixture since it was a little rich.

What a day, thanks again to my helpers to cross this great milestone!

Mags Overhaul

Received my overhauled mags last week. They were working ok but since they had just passed 500h and I couldn't find any trace of maintenance on them in the logs, I decided to make preventive maintenance and send them as recommended by my friend François. It turned out it was a good idea; one mag had a broken case and a magnet pitted by corrosion!

Both flanges were cracked like this:

Corroded magnet shaft:

Newly overhauled mags with the following replaced by new:

• one casing
• one magnet
• new contacts
• new capacitors
• impulse coupling spring
• and a bunch of little brackets and parts all in the bag shown on the first picture of this post

Thanks to Luc from BL Aviation for his great service!