New mandatory fuel tube service bulletin SB-02-23

[RV9AFlyer]

I was looking over the new mandatory service bulletin SB-02-23 regarding the fuel pick-up tube loosening for unknown reasons. I built and fly an RV-9A, and I remember insuring that my fuel pick-up tube B-Nuts were tight on both sides (actually three times). The reason that I'm writing this response is that in owning, performing my own maintenance and flying many aircraft over the past 25 years, I have a very hard time understanding the logic for this service bulletin and feel that it might actually cause more problems than hoping to solve. First of all, if the B-Nut on the fuel pickup tube needs to be safety wired, then all other critical B-Nuts on fuel and oil lines that take even more vibration should also be drilled and safety-wired. Now, in saying this, we all know that this should not be necessary and the FAA doesn't require this even on certified aircraft. From my experience, I have never seen a B-Nut that was properly tightened come loose. This brings me to only one logical conclusion--the guy that built the aircraft did not tighten the fuel pick-up tube B-Nut properly.

In being around and seeing other RV builders, I have noticed the following two builder types:

The Builder "A" Type: (this is how I did it): For every build operation, you complete the entire build sequence for that sub-assembly or use a checklist, and then inspect each sub-assembly twice (i.e. make sure the B-Nut is tight during sub-assembly and also just before installation).

The Builder "B" Type: Work on multiple sub-assemblies all at once, jumping between sub-assemblies (i.e. installing hoses and nuts but not tightening them until just before the DAR inspection). They then go back and try to tighten and safety everything up at the end. Builders I have questioned about this practice say that the DAR will find anything loose, and they don't seem too worried.

Now, if everyone opens up their fuel tanks just for one badly managed case, then I see a higher probability that builders are more likely to make a mistake and drill through the B-Nut into the threads or over tighten the B-Nut causing air to get into the fuel system when the tank is less than 1/3 full.

I understand the reason for a left and a right fuel selector is to isolate a fuel problem to one side so it does not lead to an off-airport landing, assuming that you manage the fuel system correctly.

I feel that this builder made 3 serious mistakes:
1. He was a Builder "B" type, and did not get the B-Nut tight.
2. He knew that he had a problem and continued to fly anyway.
3. He did not manage the fuel system correctly during that last flight.

These are my recommendations to Van's:
1. Educate builders on the importance of Builder "A" Type.
2. Show by this example how important locating a "fight critical" issue is.
3. Encourage RV builders to ask Van's Technical Support for input.
4. Educate RV pilots on the importance of fuel management
5. Make sure that things are tight by inspection twice or three times.
6. Educate builders on the importance of inspection during building and maintenance.
7. Maybe require flop-tubes to be safety wired due to rotation of the tubes during flight.

Van's has really designed a near perfect flying machine in my opinion. We just need to listen to what our airplanes are trying to tell us and inspect things very carefully.

John

[avaviat]

Who was the builder?

[szicree]

I started out as a type A builder, but have definitely become a proud card-carrying B type. At this stage in the project I wouldn't get anything done otherwise. For example, I'm working on my wingtip installation while waiting for some wiring supplies to arrive. Different strokes, I say.

[Ironflight]

And then there are Type C builders who jump from sub-assembly to Sub-assembly as time, mood, and supplies strike them...but also use a checklist and documentation so that everything gets looked at AND has A&P, IA, and other builder friends inspect the airplane several times before the DAR comes to town...

Just want to make the point that "jumping around" does not make one a sloppy builder.

Paul

[redbeardmark]

Then, there's the type 'F' aviator.

Exerpt from THE Service Bulletin: "The operator of this aircraft reported that, on multiple occasions, fuel would not feed from the affected tank when the level reached approximately one third full."

Let's see, been having this problem with tank A not feeding fuel. It has happened several times. It happens when the tank is 1/3 full, which is 21 gallons divided by 3, uh... that would be 7 gallons. Hmmm, so unusable fuel is now at least 7 gallons. So, plan a flight that requires more than 42-7= 35 gallons. Go flying. Draw off of tank B until it is empty and switch to tank A. And keep flying(not over the airport, mind you). Fly until no fuel will reach engine(do NOT stop to think that it has already been established that there are 7 gallons of unusable fuel in tank A, and that maybe a precautionary landing is in order to avoid damaging the airplane), land off field, damage aircraft, and BLAME VAN's. Round out day by driving through McDonald's and burning self with hot coffee...

Okay, I'm sure the pilot is a nice guy. But he deserves a good ribbing.

[RV9AFlyer]

Using a checklist is a very good idea, so a ?C? builder is most likely a safe builder, too. The service bulletin is really saying ?make sure you remember to tighten your nuts?, and don?t blame Van?s if they fall off your airplane!

John

[szicree]

Originally Posted by redbeardmark

Round out day by driving through McDonald's and burning self with hot coffee...

VansAirforce.net Comedy Award of the Day!!!

[Ironflight]

Originally Posted by RV9AFlyer

?make sure you remember to tighten your nuts?,

John

I do that everytime I snug down my harness.....


And John - you actually hit the nail on the head!

[Dgamble]

There are quite a few of us out here that did not build our airplanes, which I suppose makes us Builder Type 0. It's no small number either: of all the RVers I meet on a regular basis, the percentage that bought an already flying RV must be 30 - 35%. Personally, I see this as a testament to the quality of the design of the airplane, and I also see it as a great reason to choose to build a Van's plane over any other. When you start to build, you're probably thinking you're never going to sell it, but life has a way of changing your plans. My RV was built by a guy that lost his medical - lucky for him there is such a strong resale market for these planes.

I know this is a controversial issue for some, but many of us that didn't build our planes are doing the majority of our own maintenance, using the EAA interpretation of the FAA rules as our justification. I don't want to start another debate on whether that interpretation is right or wrong - I simply want to state the reality of the situation. Personally, I take the approach that I will do the work that I'm comfortable with and have my A&P do anything I think is beyond my skills. Others may not have that option, depending on their location and the willingness of the local A&P to work on an Experimental.

So, here we are faced with a mandatory SB from Van's. With my store bought plane, I routinely received mandatory SBs annually from vacuum pump manufacturers and other entities that are often targetted by lawsuits. They equally routinely went straight to the circular file. When something really needed fixing, the AD wasn't far behind. I suspect things are a bit different in the Experimental world, and that an actual AD is unlikely. I also recognize that Van's is very unlikely to cry wolf and that they must consider this a pretty important mattter to have taken this step.

That said, as an owner/operator I have to balance the risk of non-compliance, which I see as minimal, against the risk of making the matter far more dangerous by digging open a fuel tank. I'm lucky in that if I decide to do this, I can get an A&P to do it. I wonder how other non-builders feel about this. Are you more comfortable with leaving the tanks as-is (the devil you know) or tearing into your fuel tanks (or having soneone else do it, as I will) to address a problem that statistically probably doesn't even exist for you, at the risk of creating even larger problems?

[RV9AFlyer]

I can understand the RV pilot's feelings that did not actually build the RV he flies, and I think your percentage of non-builders flying RV's is good. I have noticed a number of builders that just like to build airplanes.

If I was concerned about how the airplane was built, I would check other B-Nuts in the engine compartment and fuel and brake lines in the fuselage. If they generally seem loose, then I might look closer. This is what my DAR told me: "if I see a trend, I look closer into that area".

A well secured fixed style pick-up tube should remain tight if it was already tight. Given that, a non-intrusive initial inspection might be a good idea. Since the fuel drain should be right under the pick-up tube, then you could drain a fuel tank after grounding the airframe, remove the drain, remove the fuel cap to let the fumes out, and then using a small diameter plastic stick with a good flashlight after grounding yourself to the airframe, lightly push on the tube in the outboard direction. If the tube starts to rotate, then you have a problem, but don't push too hard as to bend the tube.

John