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Annual Inspection – The Bakeng Deuce, Part 2
From Bits & Pieces Newsletter, August Issue
By Bill Evans, President - EAA Chapter 266, EAA 794228
August 14, 2014 - In Part 1, we mentioned that we had also done some work on the tail wheel and tail wheel steering for the ferry flight, so we decided to begin inspecting there. We were comfortable with our knowledge of that component.
We found it helpful to have a small table at hand, one with a combination wrench set and any other tools and equipment we might need. (That old table has proved invaluable every time there is work to be done.) We can wrench-check everything on the aircraft as the inspection progresses. It is further true that while visual inspection is essential, loose and worn parts do not expose their defects to eyesight alone. One handles and operates everything as the inspection continues. Every snag we found here was found by hand. For the same reason, we don’t wear gloves to inspect. Expect to get your hands dirty.
A five-day-long inspection meant that the trunk of my car was full of equipment and the backseat piled with boxes almost to the roof. Each of the five days involved one or more boxes. By day’s end, the front seat was also occupied. This is why we have spare vehicles.
One of the attendees to our 2014 forum at Sun ’n Fun International Fly-In & Expo sent us a very small but powerful flashlight. The beam can be focused. When the beam is at the narrowest, it projects grid lines which help you determine the extent of certain snags. We used that light constantly. We also used a mirror but set the mirror aside to touch the components. Wear, play, and cracked parts are detected most often by touch.
Next to the tail wheel is the empennage, or tail feathers. There are at least two controls, and if there are trim systems, then four or five controls are present. Our Sonerai has four controls on the tail; the Deuce has three. It is critical not only to examine the surfaces, hinges, and control attachments, but also that Bowden tube which houses the cable used to operate the elevator trim. The clamp that holds that Bowden cable matters a lot. If a plastic or a rubber-lined clamp is used, over time the rubber and plastic will deteriorate and crack. We have actually seen flutter start where a fastener had vibrated loose at a Bowden clamp. We’ve seen both plastic and rubber clamps used here. Go for steel!
When we certify flight controls, it is travel, safety, and soundness we are signing for. The language of homebuilding is different, but the importance is not. Now, flight controls consist of a lever, knob, or pedal of some sort, linkage, cables, tubes, and stops. The more bits, the trickier they can be. In this case, while the rudder reached the stops when the pedals were deflected, the stops were not lock wired (safety wired). Because they are both in the airstream and near the ground, it is wise to use the strongest lockwire you have. We found that .040 Inconel is ideal. It is workable but still very tough. While there, wrench check to stop nuts, then safety. If they are loose or in doubt, use a protractor to verify rudder travel.
Some control systems have stops both at the lever and at the flight control surface. At first glance, the Deuce seems to have its stops at the control surface. We don’t prefer double sets of stops. Whatever advantage may exist is outweighed by more complexity.
It suits us to bring along a can of lubricant to lube the hinges, linkages, and other fittings. Control cables fittings may well start to rust in service. A drop of oil rubbed in may stop that rust. It’s also a good idea to have a brass brush handy - similar to a toothbrush - to clean off tarnish or surface rust if it exists. Then apply a little oil and wipe off the rest. Excess oil just attracts dirt. However, don’t wipe parts dry.
So which oil are we using this year to lubricate these things? Our choices were LPS 2 at $20 a can and AeroShell 1 decanted into a small pump-oil can. It may be convenient to install about a foot of clear tubing to the oil can to reach hard-to-get-at areas. Years ago mechanics used SAE 20 nondetergent motor oil for lubricating all these parts. After spending a week with the others, we reverted to SAE 20 straight oil. It just seems better in every way to us. It’s a fraction of the price as well.
When lubricating fittings, the operative word is little. You apply a little oil. On the whole aircraft, one might use 2 ounces of oil. Always wipe off the excess with a rag or paper towel. We prefer rags because they don’t fall apart when wet. In this case, an oily rag leaves a little film of oil behind. We want that.
You may be wondering why we are doing this inspection this way. The answer is that two other flying aircraft are hangared behind ours. It is not an option to strip our aircraft and leave it in pieces. Anytime another pilot wishes to fly his aircraft, our aircraft will need to be moved.
In this situation, the inspection is undertaken in sections, which may be completed in a half-day. At the end of the inspection, the panels are closed, the checklist is updated, and we may stop if needed. In this case, it took five half-days to do just the inspection. The Deuce has fixed gear, no flaps or cowl flaps. The propeller is fixed. More complex aircraft take longer to inspect, service, and repair. The repairs may also be more expensive.