By Vic Syracuse, EAA Lifetime 180848
This piece originally ran in Vic’s Checkpoints column in the March 2020 issue of EAA Sport Aviation magazine.
I am writing this column just days after having presented an EAA webinar on Van’s RV Maintenance Gotchas. I was absolutely amazed by the participation and response. Between the 950 participants on the webinar and the 450-plus follow-on watchers of the archived webinar, that might be more than 12 percent of the RV fleet. Because I ran a little long on the webinar, there wasn’t enough time to clarify some of the topics or answer all of the questions, so I am going to try to address some of them in this column. The webinar is archived at www.EAA.org/webinars, and much of the material is relevant to aircraft other than RVs.
To no one’s surprise, I’m sure, it wouldn’t be a “Vic column” if I didn’t start with the topic of jam nuts, right? Truth be told though, there were a lot of questions surrounding jam nuts, as well as some misunderstandings. The biggest confusion — and I’ve heard it in some of my other talks — has to do with torque seal and Loctite. It is really important to understand the difference.
Torque seal is nothing but an indicator that is placed on a fitting to indicate movement. It has no locking ability at all. It is applied only after the subject fitting is properly torqued. When you take the time to apply it to all of the fittings and jam nuts on your airplane, it will make future inspections go much faster, as you only need to do a visual inspection rather than having to put a wrench on each fitting to verify it hasn’t loosened.
Unfortunately, I inspected an aircraft as a designated airworthiness representative for its initial airworthiness certificate, and the builder erroneously thought the torque seal kept the jam nuts from turning. They were all only finger tight and then had the torque seal stripe applied to them. I was impressed as I walked up to the airplane and saw torque seal on every fitting in the engine compartment, right up until I turned one with my fingers and it came loose. You can buy torque seal in a tube (it is really just thick lacquer paint), or you can steal some of your wife’s nail polish when she isn’t looking.
Loctite, on the other hand, is a product that is designed to keep a fastener from turning, usually in a high-vibration or high-stress environment. Some bearing races are installed with the green Loctite, and some engine bolts use red Loctite, such as the stud bolts that hold on the vacuum pump/standby alternators and prop governors. Loctite comes in varying strengths, the strongest of which requires heat to break it loose, so you want to use the Loctite appropriate for future removal if required. I keep the three most common types in the shop: 640 (green), 242 (blue), and 272 (red) (see picture). I use blue Loctite for stuff I know I may want to remove in the future, like baffling bolts, and red Loctite judiciously.
Someone asked if I’ve ever seen jam nuts come loose. While I know I haven’t lived long enough to see everything yet, I don’t believe they will come loose if properly torqued. I have not found a loose one on my own RV-10, which now has flown more than 1,800 hours and has had 10 condition inspections.
There also seems to be a lot of confusion with regard to operating limitations. Many owners, especially nonbuilder owners, will provide the pilot’s operating handbook when asked about the operating limitations. More than half of the nonbuilder-owned airplanes that I inspect do not have the operating limitations in the aircraft, and more often than not they are nowhere to be found. Amateur-built aircraft are issued a special airworthiness certificate, and that certificate specifically states that the operating limitations of this date are a part of the certificate. That means if they are not on board the aircraft, it is not legally airworthy.
Usually, the limitations are on three to five pages of FAA letterhead and they define the Phase I and Phase II requirements. If you don’t have them or can’t find them, they can be replaced in a couple of ways. The easiest is to find a DAR who can issue replacement operating limitations and certificates, as I do. You can also go down to your local flight standards district office (FSDO), and it will reissue them. You will get a new airworthiness certificate in both cases, as they have to match each other. You can also call the FAA Aircraft Registration Branch. It should have a copy, but there is some question as to whether or not the operating limitations in the aircraft have to be the originals.
In this same vein, for those of you who have aerobatic aircraft, you will notice that besides the required signoff for the completion of Phase I, there is also a requirement for the signoff of any aerobatic maneuvers performed in the airplane. This signoff does not have to be completed during Phase I but must be completed before passengers are carried while performing aerobatics. So, if you happened to purchase an RV that doesn’t have any aerobatic maneuvers signed off, don’t panic. I see this all the time. Again, just go perform the maneuvers and place the entry in the logbook. The only catch is that if you have moved the airplane outside of the initial test area defined in the operating limitations, you might want to call the local FSDO for a new test area.
Another area of confusion has to do with safety-wiring the wheelpants brackets. More than half of the airplanes I inspect are missing this safety wire, even though they have a drilled head bolt installed, which should be a clue. There are two ways of accomplishing this. You can either drill a hole in the bracket itself and attach the safety wire to it, or attach the safety wire to the cotter key in the axle nut.
Since my column last month on intake gaskets, there have been a few questions regarding the power setting required to check for intake leaks while flying. I guess I wasn’t clear enough. The idea is to close off the intake system with the throttle plate so that the engine will now suck air through any leaks that are downstream from the throttle plate, which are usually the intake hoses or gaskets. So, pulling the throttle to the stop while on base is a good way to accomplish this. Then just watch for a rising EGT indication on one or all of the cylinders to find the leaks.
Spark plug washers also seem to cause some confusion, specifically where to use them and their orientation. If you take a close look at the common 18-millimeter copper spark plug washers, they have a flat side and a convex side. The flat side should go toward the spark plug. These washers should be used underneath every aviation spark plug, as well as the spark plug adapters that allow the use of automotive spark plugs for electronic ignition systems. I install new washers every time I remove a spark plug, whether it be for cleaning, inspection, or compression check. I know you can reuse them if you take the time to anneal them properly, but at a purchase price of 30 cents each, reusing them is just not worth it to me.
With regard to not using RTV silicone around fuel, someone asked why it couldn’t be used to fill the gaps around the outside of the carburetor where it attaches to the airbox. First, while RTV does have resistance to oil, that applies when it is used to mate two closely machined parts. It is not meant to fill large gaps. My experience has been that there is usually oil on top of the air box from engine leaks and smoke systems, and the RTV tends to become dislodged. I find Proseal to be a better choice.
Again, thanks to those of you who are now looking at your airplanes more closely with some newfound information. It’s a way to keep the fun factor alive! I also am hoping that those of you who participate in active EAA chapters will consider having a “preflight your buddy’s aircraft” activity during a meeting and report on the results. Another set of eyes is a really good thing.
Vic Syracuse, EAA Lifetime 180848 and chair of EAA’s Homebuilt Aircraft Council, is a commercial pilot, A&P/IA, DAR, EAA flight advisor, and EAA technical counselor. He has built 11 aircraft and has logged more than 9,500 hours in 72 different types. Vic also founded Base Leg Aviation and volunteers as a Young Eagles pilot and an Angel Flight pilot.