Accident Antonov An-12AP RA-11125,

ASN Wikibase Occurrence # 321075

Date:	Tuesday 9 August 2011
Time:	15:32
Type:	Antonov An-12AP
Owner/operator:	Avis-Amur
Registration:	RA-11125
MSN:	3341006
Year of manufacture:	1963
Total airframe hrs:	18709 hours
Cycles:	9172 flights
Engine model:	Ivchenko AI-20M
Fatalities:	Fatalities: 11 / Occupants: 11
Aircraft damage:	Destroyed, written off
Category:	Accident
Location:	86 km SW of Omsukchan - Russia
Phase:	En route
Nature:	Cargo
Departure airport:	Magadan-Sokol Airport (GDX/UHMM)
Destination airport:	Keperveyem Airport (UHMK)
Investigating agency:	MAK
Confidence Rating:	Accident investigation report completed and information captured

Narrative:
An Antonov 12 cargo plane, RA-11125, crashed about 86 km from Omsukchan, Russia. The airplane carried 11 occupants and 17,43 tons of cargo, consisting of amongst others consumer goods, food, auto parts, and medicines.
Avis-Amur Flight 9209 had departed Komsomolsk-on-Amur on a flight to Keperveem with a refuelling stop at Magadan. The An-12 landed at Magadan at 12:54 after an uneventful flight.
The flight was refuelled and departed Magadan at 14:37 for the final leg of the flight. The cruising altitude of 7500 m was reached at 15:17. Shortly afterwards, a fuel leak was noted in the no. 4 engine. At 15:22 the crew requested a descent to 6600 m, and a return to Magadan. This was approved. The crew shut down the no. 4 engine and feathered the prop. The engine was on fire, and at 15:27 the crew reported the fire and stated that they were conducting an emergency descent.
The crew had reported a fuel leak and an engine fire and indicated that they were returning to Magadan. The airplane did not reach Magadan and contact was lost.
The wreckage was located the following day and no survivors were found.
RA-11125 was the oldest plane of the Russian commercial air fleet.

CONCLUSION (translated from Russian):
The cause of the crash of the An-12AP RA-11125 was the loss of lateral control because of the loss of bearing properties of the left wing of the plane and a possible violation of the integrity of the control wiring rod of the left aileron, which led to intensive airplane rotation with a roll to the left and the collision with the slope of the mountain.
The cause of the loss of the bearing properties of the airplane's left wing and a possible violation of the integrity of the left aileron control rod wiring was a fire, arising in flight at the aft compartment of the engine nr.1 nacelle which spread to the wing.
The fire most likely started when leaking fuel from fuel line connections from the nr. 1 engine low-pressure pump ignited in contact with a hot part of the engine. Due to the complete destruction of the aircraft, it was not possible to clearly establish the place and cause of the leak that led to the leak of fuel.
Impossibility of extinguishing the fire at an early stage by a fire fighting system could have contributed to a delay in engine nr. 1 to be turned off (at least 2 minutes after the fuel leak detection) due to lack of An-12 crew instructions on actions at fuel leakage from under the engine cover in flight.
Mountainous nature of the underlying terrain, the lack of visibility over land because of overcast cloud and lack of time due to the ongoing fire, did not allow the crew to choose a site and make an emergency landing.

Accident investigation: