On Wed, 25 Apr 2007 12:15:08 -0400, john smith
wrote:

Once-upon-a-time I allegedly was asked to bid an insurance job on a
Turbo Arrow IV.

The airplane involved was on it's way to the East Coast to cross the
big pond.

Was cruising around 10,000 ft msl over a local rural county airport
with a 4200 ft runway (750 ft msl) when a fitting failed on top of the
turbo.

The fitting had apparently been added to tee an hourmeter oil pressure
switch into the oil pressure supply line to the turbo. If I remember
correctly, this supply line is also tee'd to the oil pressure gage in
the cabin.

When the fire erupted, the pilot secured the engine (fuel selector
prop mixture mags master), dropped the flaps and gear, and descended
in a slipping circular pattern to the field, and landed/rolled out on
the runway.

Being a single-engine constant-speed NON-feathering propeller, the
engine continued to windmill, the engine-driven oil pump emptied the
engine sump oil though the failed fitting, feeding the fire.

The first thing that I noted when examining the 'plane was that the
bracket that the extend retract cylinder mounts to on the bottom of
the firewall/belly angle was only attached by a small portion of the
firewall. the belly skin behind it was burnt/virtually gone. The
bracket was rotated down/forward approximately 60 degrees from it's
"normal" position.

Damage forward of the firewall was localized "below" and "aft" of the
broken fitting. I do not recall the firewall being perforated, but the
upholstery material/insulation blanket on the cabin side of the
firewalll showed signs of some serious heat.

The belly skin was rippled from the firewall to where the fuselage
bottom "breaks" upward to the empennage, between the center hat
sections that run longitudinally on the belly. The belly skin was
perforated immediately behind the firewall, but only (only??!!) had a
couple of small holes in it. The carpet/tunnel trim down the center of
the cabin had evidence of overheating, and several burnt spots.

As I recall, the bottom cowling was heat-damaged, but the only place
the fire exited the cowling was out the center nose gear opening.

IMHO, the pilot did exactly the right thing. I would "dirty-up" the
airplane with whatever I could hang out in the breeze so I could
descend at the highest rate.

Have never experimented with time to descend dirty vs. clean, but I do
know that it takes f-o-r-e-v-e-r to come back down clean after doing a
turbo critical altitude check.

Have also allegedly burned a couple of brush piles, and there ain't
nuthin that burns quite like an old tire...

Long story short, haven't been there done that, but I've seen it done.

TC

One of the aircraft I fly is a 1982 Piper Turbo Arrow IV.
Nowhere in the POH does it mention the emergency procedure for a
turbocharger failure resulting in an oil fed fire in the engine
compartment.

Do you drop the gear or leave it up?

My thinking is to drop it to keep the nose gear tire from being consumed
as additional fuel and to move more air through the engine compartment
while in a dive/steep descent to blow out a fire

Anyone with actual experience?