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!

Some Flying!

Following first flight, I have been flying quite a bit. Getting back into pilot mode is a blast! Each second of practicing landings as well as aerobatic figures in this finely balaced aircraft is exquisite. The hard work on the rebuild was totally worth it.

Before the rebuild, my partner Luc and I used to have a routine after our respective aerobatic practices: perform 5-6 tight circuits together at our home airport. Durign the rebuild, we both dreamed about getting back into this routine together. We could finally do it!! What a feeling. Thanks Luc! We also went to the Green Mountain Aerobatic Contest together. François, a friend of us took great pictures:





Thanks to all IAC 35 team that organised this great contest!

Not too long after getting back from the contest, I found a unpleasant surprise under the cowling. Will dedicate another post on this...

The great day I flew again for the first time

After lonnng weeks of waiting for suitable weather, I finally saw a sun pictogram in the local forecast. It was a Tuesday and it was going to be sunny, fresh, with calm winds; just perfect. Took a day off to make sure I wasn't rushing for daylight after work. I wanted to take my time to make sure both myself and the machine were ready. Moreover, week-ends here in Lachute airport can get quite busy, so it was worth shooting for a week day to avoid too much airplanes in the pattern.

I spent the night before doing a thorough walkaround, checked fuel, oil, tire pressure, and plugged the battery on trickle charge overnight. I started feeling the rush as I finished preparing the airplane and closed the hangar door that night.

Morning air was fresh, with a clear blue sky. Winds were calm and forecasted to pick up slightly during the day, but along the runway axis. Took the time to refresh my memory on the key items noted during the flight I did with my friend Luc in his S-2C the week before e.g. the things to remember, common mistakes to avoid, etc. The plan was to perform braking tests during taxi, run-up, then take-off and climb at 100 mph along runway axis until 2000 ft then turn-around while continuing the climb until 3000 ft which is the limit of the airspace. Then I was going to check engine parameters upright + inverted as well as stall characteristics.

Didn't put the wheelpants for first flight to ease post-flight inspection of the brakes. The taxi tests went well. Brake pedals were not spongy at all. After a couple of S turns and brake tests, the engine began sounding a little different, similar to plug fouling. After a run-up and a higher power run on the runway, it didn't improve much so I decided to turn back and inspect + clean the plugs. Turned out #2 cylinder plugs were quite dark indicating a rich mixture. This was in accordance to a flow divider test I did a few weeks before. I therefore decided to install a smaller restrictor to the #2 injector (Airflow Performance).  I also adjusted the idle mixture, cleaned the plugs and fit the cowl back on. Turned out it got improved so I taxied pyaing extra care about the mixture, did another run-up, took off and sticked to the plan. Although I was concentrating on what I had to do, the back of my mind was exhilarated by the acceleration feeling on the runway, especially the first few seconds in the air. Once at 3000ft, checked oil temp, oil pressure upright/inverted, fuel pressure upright/inverted with/without boost pump, checked CHTs and all was in-line with expectations. Did a mag check and got a few subtle backfires on RH mag that immediately disappeared when I switched to LH or both. This turned out to be my only snag. All the rest, including stall characteristics and hands off trim were surprisingly good. 

Just like the WW1 fighters, I looked down waiting for the perfect opportunity to dive and join the pattern. Carried a little extra speed in the approach to ensure good control authority all the way down to the flare. Plan was to do a full stop unless otherwise required. Landing the airplane after all this time felt amazing. 32 min flight total, 1 snag BNF (like they say in flight test: to be fixed Before Next Flight). Mission accomplished!

I remember when I almost had a syncope as I was preparing for the 2015 season. It was then the beginning of a looonnnng project...  Two years of work in total, little by little, spending evenings after work and week-ends at the hangar. I would be lying if I said that there was no phase of discouragement, but thanks to the help of my family and friends, and to you readers of my blog, I finally got back in the air with this little biplane so enjoyable to fly. When I think back of this first flight, the feeling of being at the controls of an airplane that I completely assembled was very peculiar, as if I was feeling all the small mechanisms moving behind each of my movements.

I want to thank my girlfriend Isabelle: you encouraged me all along, helped during the reassembly and supported my many days of absence, thank you! My father Victor for the important help during key stages of the reconstruction: engine and wings reinstallation as well as your help for the preparation of the first engine start and the first flight. Thanks to my mother Danielle for encouraging me relentlessly. Francois Marquis for countless technical advice at each stage of the reconstruction, and also for having supported the multiple, very educational words I pronounced on the phone when I realized what this crack meant. Thanks to Luc Martineau for keeping my morale up every time we crossed path at the hangar, for your help during the wing reinstallation, for your solid assistance during the first flight and especially for having supported my mess in the hangar during all this time. Thanks to Scott Black for the hundred tools I've borrowed from you and the many manufacturing tips and valuable references, as well as your help with W & B and parts machining, you were always there, ready to help. Thanks to Mark Clément for the excellent and precise welding work, your multiple trips to Lachute and your special care to understand what I needed. Thank you Paul Goyette for your precious time and your incredible attention to detail and patience that allowed me to make the trim tab and wing rigging tool. Thanks to Marc-Antoine for help in repairing the left wing attachment bracket, baffle, longeron brackets, as well as the many encouragement and our flights in the Citabria that helped me stay on tracks and fulfil my lack of vitamin G. Thanks to Jocelyn Côté for your patience, the multiple top quality parts refurbishments, and technical advice. Thanks to Mathieu Gratton for the great help in writing the logbook entry and mod report for the local authorities. Thanks to Raphael Langumier for your procurement help. Thanks to Francois Bougie for allowing me to visit the Pitts International Archives which got me crucial information for the repair. Thanks to Russ Larsen for helping with the final inspection and driving into crappy weather afterwards. Thanks to my friends from Wichita: Jeff Hyde for technical advice and very educational workshops at your hangar, Chuck Ellis for the unparalleled airmail service exclusive to aircraft building parts, Mark Wood for help with the fuel system redesign and the idea of ​​the siphon valve, Ben Van Kampen for great tech tips. Thanks to Wes Liu for sharing the idea of ​​split nosebowl attachment. Thanks to Dani for helping during wing reinstallation. Thanks to Francois Viau for help during the propeller reinstallation. Thanks to Peter Ashwood for the encouragements and information on the S-1T. Thanks to Bill on Biplane Forum for sharing the plans of the rigging boards. Thanks to Richard Perron for the multiple tool loans. Thanks to Pierre Bérichon for the loan of the shop crane which lasted a lot longer than expected. Thanks to Claude Camirand for the mag drill. Thanks to the team of Griffon Technical Services who have helped me several times. Thanks to Luc from BL Aviation for the quality service during the inspection of the magnetos. I'm deeply sorry if I forgot anybody and still thank you! I also want to thank again the readers of this blog; knowing that what I was writing wasn't too boring certainly helped keeping the momentum!

Thanks again to all of you that helped me throughout this long project. You made all the difference, both for technical and moral support. Each one of you made the dream to fly again in this airplane possible.

I will continue updating this blog with updates on my activities with my Pitts so feel free to come back now and then!

Cheers,

-Dimitri

While the rain is falling - New hangar mezzanine

I plan to fly with my friend Luc in his S-2C to get back in the groove of flying a Pitts. However, Wx over the last two weeks in our area has not been suitable for flight; it rained so much that many places are flooded. We therefore took the opportunity of this crappy weather to work on an important improvement to the hangar: a mezzanine.

There wasn't even a toilet in the hangar before. In winter at -20°C outside, jettisoning your unusable fuel can be painful. This mezzanine has many important new features that will make the time spent in our Pitts stop more enjoyable:

• Washroom
• Hot water
• Kitchen area with microwave, sink, small stove and fridge
• More storage room
• More light
• Better sound
• Dedicated spot for de-humidifier 
• Clean area for flight preparation, documents and books
• Security camera

Our friend Joe was kind enough to put our birds in his hangar free of dust for two weeks. Here is how our spot looked like before starting the work:

Initial structure work, very well done by Rich, the carpenter of the airport:

Bulk of the structure completed:

Working on the fence + table finishing. Note the ledge to minimize the risk of dropping something:

Epoxy coat:

Almost done:

Spent a lot of time to reorganize the storage:

Final shot, ready to roll the airplanes back in!

It was raining cats and dogs so we'll move the airplanes later : (

Big thanks to my friend Luc for the great initiative. It will definitely enhance the hangar experience. We can actually receive people now so if you come up in the area and stop in CSE4, feel free to drop me a line to meet us at our new Pitts stop!

Stay tuned for the next update on the Pitts : )

Removal of exhaust wrap

The other day I was driving to the hangar just like I routinely did for the last two years, but when I arrived, I realized I was almost at the end of my to do list (!)

I am waiting for a few small replacement parts that are not critical for first flight. I am also waiting for the availability of the local maintenance shop here in CSE4 to inspect my airplane. Strictly speaking, I could legally take-off, but having a second pair of eyes going through my work is not a luxury imho, especially since I have been closely into it for a long time.

While in waiting mode, I made a little research on the benefits of having fibreglass wrap around the exhaust. The wrap I have was installed when I bought the airplane, but it was getting very dirty and hairy.

I found this thread on the Vans Air Force forum which pointed to the Vetterman Exhaust website. Here is an extract of the website in question:

Can I wrap my exhaust with automotive type of wrap material and obtain more power? 

Any material on the exhaust will shorten it's life and failure will occur. We are using air cooled engines and one the best heat sinks on the engine is the exhaust system. The mass air flow comes in and is forced down and around the cooling fins and then is directed over the exhaust system and then exited out the bottom. If the exhaust is covered it cannot aid in the cooling process. Our tests show that any type of wrap on the exhaust makes both the cylinder head and exhaust temperature run higher. The stainless steel used (type 321) will degrade if the surface temperature is over 1250 degrees F. We also did not find a power increase of any kind by wrapping the exhaust.

More weight. Less cooling, no additional performance. Hmmm.

I also checked pictures of the Red Bull Air Race airplanes and confirmed that they don't use such exhaust wrap. I guess if it was creating any major power increase, these guys would use it!

The other reason a previous owner could have needed to use such wrap is perhaps to limit heat radiation in the bottom cowl. I never had any oil temp issues in this airplane...

I finally decided to remove the wrap, but keep a close eye at my oil temp during the first few hours of operation. 

It was a mess. At some point I had to put a mask to avoid breathing all the fiberglass dust flying around. Some guys say that exhaust wrap also traps moisture. What I found underneath tends to confirm this:

It was only surface corrosion that could easily get wiped off, but still... Here's what the whole thing looked like once removed from the airplane:

I was expecting to save about 1/2 lb, but with all the steel clamps, it was weighing close to 1.5 lb!

Finally I cleaned the exhaust using water with mild soap. This was enough to remove most of the old wrap traces. Looked nice and clean at the end.

What could I do next? Perhaps getting some dual time on a nice red S2C would be a good idea!

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!

Wing Rigging - Wire Tension Progression

Before doing the W&B, I rigged the wings using the recommended procedure in the Christen Eagle AFM.

From past experience, a biplane wing rigging is never a straightforward process. Since I was crazy enough to buy a digital torque wrench, it gives me the possibility to quite quickly and accurately read the wire tension (along with the tool from Holloway Engineering). I therefore made an experiment: record all wire tensions for every iteration of the tensioning process on one side. This way I was going to hopefully capture the converging tendencies and learn as much as possible to hopefully ease future riggings.

The following graph summarizes the results I got during the tensioning of the RHS wing wires. Each bar height is proportional to the wire tension. When a label exists above a bar, it means this wire has been adjusted compared to the last iteration. For example, on iteration 2, the fwd landing wire has been tightened by 1/2 turn. Negative values mean wire loosening. The brackets on the bottom indicate the results of the readings from the level I placed over the top wing front spar.

I could note/confirm the following trends for my aircraft:

1. When tensioning one wire in a pair, the other wire of the same pair often looses tension (see landing wires during iterations 1,2 and 3)
2. Adding tension can be done relatively gradually whereas removing tension can easily be drastic (see iteration 7)
3. Adding tension on the flying wires does not significantly add tension on the landing wires (see iteration 4)
4. Adding tension on the landing wires can have more of an effect on the flying wires (see iterations 5 and 6)
5. Building tension on the flying wires has to be done with care since it can bend the wing and cause undesireable anhedral. In this example, I caused a slight anhedral up to iteration #6, then I removed tension on the flying wires on iteration #7 to remove the anhedral. In other words, it seems to be preferable to tighten the flying wires only when there is already quite some tension on the landing wires.

After iteration #13, I switched to other side to tension the LHS wing, then when back to RHS and did small adjustments to get within tolerances. After all that, I measured the wing incidences with the rigging boards and quite happily confirmed they were within tolerance too! This seems easy to summarize, but the whole process took me around 2 days of work.

I do not pretend the above is applicable to any other biplane, but perhaps a potion of the above findings can help others : )

Next step: the first engine startup. Stay tuned!