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Thursday, March 9, 2017

Report: Uncontained engine failure brought down IL-76 near Karachi, Pakistan in 2010


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Accident description
Last updated: 9 March 2017
Status:Final
Date:Sunday 28 November 2010
Time:01:45
Type:Silhouette image of generic IL76 model; specific model in this crash may look slightly different
Ilyushin 76TD
Operator:Sun Way
Registration:4L-GNI
C/n / msn:43452546
First flight:1984
Total airframe hrs:8357
Cycles:3373
Engines:4 Soloviev D-30KP
Crew:Fatalities: 6 / Occupants: 6
Passengers:Fatalities: 2 / Occupants: 2
Total:Fatalities: 8 / Occupants: 8
Ground casualties:Fatalities: 3
Airplane damage:Destroyed
Airplane fate:Written off (damaged beyond repair)
Location:ca 5 km W of Karachi-Jinnah International Airport (KHI) (   Pakistan)
Phase:Initial climb (ICL)
Nature:Cargo
Departure airport:Karachi-Jinnah International Airport (KHI/OPKC), Pakistan
Destination airport:Khartoum-Civil Airport (KRT/HSSS), Sudan
Flightnumber:4412
Narrative:
An Ilyushin 76TD cargo plane, registered 4L-GNI, was destroyed in an accident near Karachi-Jinnah International Airport in Pakistan. All eight occupants and three persons on the ground were killed. 
The airplane operated on a cargo flight from Karachi-Jinnah International Airport (KHI), Pakistan to Douala, Cameroon with a planned en route stop at Khartoum, Sudan. The flight was loaded with 30.5 tons of relief supplies (tents).
After completion of necessary pre flight requisites by the flight crew, the cockpit crew contacted Karachi Airport at 01:14 hours local time and informed about their readiness to start for Khartoum. After receiving permission from the air traffic controller, the crew started the engines between 01:21 and 01:24. On previous flights the crew had encountered problems starting engine no.4. On those occasions the engine was finally started after switcing on the Engine Anti Ice System. At Karachi, the flight crew proactively activated the Engine Anti Ice System before starting engine no.4.
The most probable reason of abnormal starts of the engine no.4 was reduction of compressor efficiency because of blade wear. The service wear of blades increases axial and radial clearances and the blade surface becomes rough, thus reducing the compressor efficiency. With the inlet guide vanes heating mode on, the amount of air through the compressor’s first stages increases thus improving the start reliability.
The crew then taxied the plane to runway 25L and took off at 01:43 hours. Shortly after takeoff, as the aircraft was climbing through an altitude of 100 meters, the no.4 engine suffered an uncontained failure. The airspeed was 325 km/h and undercarriage had been retracted. The remaining three engines continued working on takeoff power.
The aircraft banked right, which the pilot tried to counteract with ailerons and rudder. The no.4 engine was then set to idle and subsequently shut down. 
Despite fully deflected ailerons and spoilers to create a left bank, the aircraft continued in a right bank. Right bank had increased to 32° while the recorded deflection of the rudder was -24° (to the left) and elevator to -10° for pitch up. The aircraft reached a height 140 m before it entered a descent.
At 01:44 the bank angle became 71° to the right and the aircraft continued moving to right and impacted buildings that were under construction.

Probable Cause:

Cause of Occurrence:
The cause of the occurrence was uncontained failure of the 2nd stage disk of LP compressor of Engine # 4 due to fatigue fracture which resulted in in-flight fire and damage to adjacent areas of right wing / flaps to an extent that flight could not be sustained.
The use of mishap engine beyond its manufacturer’s assigned life without assessment and life enhancement by the manufacturer was the cause of its uncontained fatigue failure.

Sources:

Official accident investigation report
cover
investigating agency:PakCAA
report status:Final
report number:Final report
report released:3 March 2017
duration of investigation: 6 years and 3 months
download report: Final report

Follow-up / safety actions
PakCAA issued 14 Safety Recommendations 
Show all AD's and Safety Recommendations
Photos

photo of Ilyushin 76TD 4L-GNI
photo of Ilyushin 76TD 4L-GNI
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Map
This map shows the airport of departure and the intended destination of the flight. The line between the airports does not display the exact flight path.
Distance from Karachi-Jinnah International Airport to Khartoum-Civil Airport as the crow flies is 3721 km (2326 miles).
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