Stay away from RTV near fuel

LettersFromFlyoverCountry · #1 04-09-2015, 05:44 PM

The NTSB this week released the probable cause of an RV-10 crash (I'm not saying where nor who because I don't want to open that can of worms and have people miss the important point) last year in which two people died.

There were two important takeaways.

(1) Don't use RTV* in a fitting in the fuel line.

(2) If someone with lots of experience and knowledge says "don't do that", then don't do that.

* Or Teflon tape.

Carry on

Sig600 · #2 04-09-2015, 08:47 PM

What was the use of RTV? We're they trying to fix a leak or a bad flare?

aerhed · #3 04-09-2015, 09:19 PM

Floscan has pipe thread. You can see RTV used for the threads and some stuck inside the Floscan. No further comment.

rightrudder · #4 04-09-2015, 11:01 PM

A little smear of Loctite 567 would've been perfect.

Walt · #5 04-10-2015, 05:51 AM

A good example of how "it's what you don't know that will kill you". Chances are the offending substance was also used upstream on the fuel valve as the blockage was in the inlet of the FF xdcr line.

BillL · #6 04-10-2015, 05:58 AM

I saw an engine oil pump that had ingested a slug of silicone RTV and it fractured the housing caused an engine failure. Oil pressure was high enough not to trip the pressure switch, but not enough to lube the engine.

RTV is only to be used in rare, very rare, situations for engine related sealing. And sparingly if used at all. Slugs of excess are just one of the failure modes, but is at the top of the probability list.

Mark Dickens · #7 04-10-2015, 07:19 AM

I can't think of a case where RTV would be ever indicated FWF. AN fittings are assembled dry and NPT fittings (like the one on the fuel flow sensor) require an aircraft-grade thread sealant like Tite-Seal. Where would RTV be the best approach anywhere FWF?

Mike H · #8 04-10-2015, 07:32 AM

It is very saddening to learn that something so simple and obvious to most caused loss of life.

Regarding other comments stating to never use Teflon tape on threads. There is a type of Teflon tape made specifically for fuel and oil use, and I have used it many times on aircraft. Yes it can cause blockages is it is applied incorrectly, but so can Teflon pipe dope.

ChiefPilot · #9 04-10-2015, 07:48 AM

Quote:

Originally Posted by Mark Dickens

I can't think of a case where RTV would be ever indicated FWF. AN fittings are assembled dry and NPT fittings (like the one on the fuel flow sensor) require an aircraft-grade thread sealant like Tite-Seal. Where would RTV be the best approach anywhere FWF?

Anywhere FWF? Sealing various areas on the baffles comes to mind...

Mark Dickens · #10 04-10-2015, 08:55 AM

Quote:

Originally Posted by ChiefPilot

Anywhere FWF? Sealing various areas on the baffles comes to mind...

Sorry, I meant on the engine. I know you can use it to secure wiring, plug holes, provide chafe protection, etc. Even then you need to be careful of which product you're using and the substrates on which you're using it.