X-Mozilla-Keys:                                                                                 
Finn Lassen wrote:

I thought I better share today's experience in the hope that others may
learn from my mistakes.

Following Tracy Crook's advice, I tied down my RV-3 to make a full
throttle run-up of my Mazda 13-B rotary engine installation prior to any
first flight.

I ran the engine for maybe 1 - 2 minutes, shut it down, waited a couple
of minutes and did another engine run-up for another couple of minutes.
Suddenly, when throttling down, I noticed orange frames coming out my
left cowl cheek (left open - no cone). Instead of doing what I should
have done (shut off fuel pumps and turned fuel valve off and shut down
engine), I first tried to blow out the fire by adding throttle. That
produced a much bigger orange flame. By then smoke had started to appear
in the cockpit so I shut down the engine and got out, bringing my little
foam extinguisher with me. I successfully put out the fire by emptying
it into the left cowl cheek opening.

Meanwhile, the FBO line guy had arrived with a bigger extinguisher and I
had him stand by while removing the cowling.

By inspection of the engine installation I found that the oil hose had
ruptured where it passes by the exhaust pipe. Apparently the hot exhaust
pipe had ignited the oil. That fire then reached higher and melted the
(polyurethane) fuel lines near the fire wall. I'm still not sure if they
melted close or if they added fuel to the fire.

All this seemed simple to fix:
Route the oil hose further from the exhaust pipe with a heat shield in
between and add fire sleeve.
Use rubber fuel lines with fire sleeves.

However, upon closer inspection of the plane, I found that the bottom
skins of the flaps had melted. All bottom skins all the way out to the
tail wheel had deformed, and the rear bottom skin had actually torn. The
right elevator bottom (the wind had blown the flame from left to right
under the fuselage) was also deformed. The rear bottom wing skins were
also deformed for about 10 to 20 inches out on each side.

It is very possible that the damage would have been limited if I had
drilled engine fire procedure.

Seems that now I have no alternative than to:
Remove wings and  tail section and truck the parts home for a fuselage
rebuild (and replacing inner wing bottom skins).

It may be easier (and safer) to simply build a new fuselage. If anybody
knows of an RV-3 fuselage kit (preferably untouched - not started) for
sale at a good price, please do contact me (finnlassen@netzero.com).

If anybody have any good ideas on how to repair the fuselage without
removing the rear top fuselage skin I'd be happy to hear about it.

So much for flying this Century.

Moral of the story:
Do a failure analysis of all parts of engine installation (what if?).
Drill engine fire procedure before starting engine - even for the first
time.

I lucked out - it could have been much worse - could have happened in
the air. Thanks to Tracy for saving my bacon!

Finn

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