Pakistan International Airlines Flight 17 was a scheduled domestic flight from

Dacca Dhaka ( or ; bn, ঢাকা, Ḍhākā, ), formerly known as Dacca, is the capital and largest city of Bangladesh, as well as the world's largest Bengali-speaking city. It is the eighth largest and sixth most densely populated city i ...

to Faridpur in

East Pakistan East Pakistan was a Pakistani province established in 1955 by the One Unit Scheme, One Unit Policy, renaming the province as such from East Bengal, which, in modern times, is split between India and Bangladesh. Its land borders were with India ...

(now

Bangladesh Bangladesh (}, ), officially the People's Republic of Bangladesh, is a country in South Asia. It is the eighth-most populous country in the world, with a population exceeding 165 million people in an area of . Bangladesh is among the mos ...

) operated by a

Sikorsky S-61 The Sikorsky S-61L and S-61N are civil variants of the Sikorsky SH-3 Sea King, SH-3 Sea King military helicopter. It was developed and produced by the American helicopter manufacturer Sikorsky Aircraft. The commercial version of the Sea King w ...

twin-engined helicopter of

Pakistan International Airlines Pakistan International Airlines ( ur, ; abbreviated PIA, ur, ) is an international airline that serves as the national flag carrier of Pakistan under the administrative control of the Secretary to the Government of Pakistan for Aviation. It ...

. On 2 February 1966 the helicopter operating the flight crashed near Fardipur after an oil leak developed and the main gearbox failed. Twenty passengers and all three crew were killed; one passenger survived.

Accident

The S-61, registered ''AP-AOC'', left

at 14:03 local time on 2 February 1966 and within 15 minutes an oil leak had started from a pipe connected to the main gearbox. The flight continued and while the helicopter was at an altitude of 500 feet (152 m) crossing the

Padma River The Padma ( bn, পদ্মা ''Pôdma'') is a major river in Bangladesh. It is the main distributary of the Ganges, flowing generally southeast for to its confluence with the Meghna River near the Bay of Bengal. The city of Rajshahi is sit ...

the sole survivor noticed that the oil leak was visible in the passenger cabin. About 3.5 miles (5.6 km) from Faridpur

heliport A heliport is a small airport suitable for use by helicopters and some other vertical lift aircraft. Designated heliports typically contain one or more touchdown and liftoff areas and may also have limited facilities such as fuel or hangars. I ...

, a

bird strike A bird strike—sometimes called birdstrike, bird ingestion (for an engine), bird hit, or bird aircraft strike hazard (BASH)—is a collision between an airborne animal (usually a bird or bat) and a moving vehicle, usually an aircraft. The term ...

occurred, with a

vulture A vulture is a bird of prey that scavenges on carrion. There are 23 extant species of vulture (including Condors). Old World vultures include 16 living species native to Europe, Africa, and Asia; New World vultures are restricted to North and ...

hitting one of the rotor blades on the left side of the helicopter. The helicopter continued normally and the pilot lowered its landing gear at an altitude of 300 feet (91 m) in preparation for the scheduled landing at Faridpur. Although both engines were running the helicopter experienced a loss of power to the main transmission; the pilot corrected the resulting turn to the left, then the helicopter continued rolling and rocking in a steep uncontrolled descent into the ground at 14:23.

Probable cause

The accident was attributed to the disengagement of the left and right spur gear teeth in the main transmission, caused by the load imposed by the failure of the gearbox's rear sleeve bearing journals. The rear sleeve bearing failure was caused by an oil leak although evidence was destroyed by fire and the source of the leak was not established.

References

{{coord missing, Pakistan Aviation accidents and incidents in Pakistan Accidents and incidents involving the Sikorsky S-61 17 1966 in Pakistan February 1966 events in Asia