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Last updated: 5 March 2021
Statuts:Enquête Officielle
Date:vendredi 21 avril 1995
Heure:16:05
Type/Sous-type:Silhouette image of generic B742 model; specific model in this crash may look slightly different
Boeing 747-2F6B
Compagnie:Philippine Air Lines
Immatriculation: N742PR
Numéro de série: 21833/423
Année de Fabrication: 1980-01-07 (15 years 4 months)
Moteurs: 4 General Electric CF6-50E2
Equipage:victimes: 0 / à bord:
Passagers:victimes: 0 / à bord:
Total:victimes: 0 / à bord:
Dégats de l'appareil: Substantiels
Conséquences: Repaired
Lieu de l'accident:15km SE of Sydney-Kingsford Smith International Airport, NSW (SYD) (   Australie)
Phase de vol: En vol (ENR)
Nature:Transport de Passagers Intern.
Aéroport de départ:Sydney-Kingsford Smith International Airport, NSW (SYD/YSSY), Australie
Aéroport de destination:Manila-Ninoy Aquino International Airport (MNL/RPLL), Philippines
Détails:
During a scheduled transit stop, the number 1 engine (CF6-50E2) of the Boeing 747-2F6B required three engine starts for the rectification of a minor oil leak and troubleshooting of other defects before the aircraft was subsequently released for service. Soon after departure from Sydney-Kingsford Smith International Airport, Australia, whilst climbing through 8,500 ft at 263 kts, the pilot in command noticed that the number 1 engine start valve OPEN light was illuminated and he requested the engine shutdown checklist. Almost immediately, whilst disconnecting the auto-throttle, there was a bang, a slight yaw to the left and vibration for a very brief duration. During the engine shutdown sequence, the engine fire detection light on the centre panel illuminated momentarily.
After securing the engine, 30 tonnes of fuel was jettisoned before the aircraft returned to Sydney for an uneventful landing.

Inspection on the ground revealed that only the top sections of the fan cowls, containing the hinge fittings, remained on the number 1 engine. The forward section of the pylon, and the wing leading edge outboard of the pylon, were holed and dented. The paint on the starter case was blistered and there were detached turbine blades in the starter exit screen.

Probable Cause:

SIGNIFICANT FACTORS
1. A fuel leak occurred from a loose connection in the environmental drain system of the number 1 engine which pooled in the area above the starter.
2. The fuel evaporated to form an explosive mixture in a contained, unvented area within the fan cowls during flight.
3. The engine start valve opened, uncommanded, in flight.
4. The starter oversped and disintegrated, having no engine load to contain its speed.
5. The hot liberated debris from the starter ignited the explosive fuel-air mixture.
6. The subsequent explosive force deformed the cowlings into the high speed airstream, resulting in overload failure of the cowl latches and loss of the cowl panels.

Accident investigation:
cover
Investigating agency: BASI
Status: Investigation completed
Duration: 1 year and 4 months
Accident number: 199501217
Download report: Summary report


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Plan
Ce plan montre l'aéroport de départ ainsi que la supposée destination du vol. La ligne fixe reliant les deux aéroports n'est pas le plan de vol exact.
La distance entre Sydney-Kingsford Smith International Airport, NSW et Manila-Ninoy Aquino International Airport est de 6245 km (3903 miles).

Les informations ci-dessus ne représentent pas l'opinion de la 'Flight Safety Foundation' ou de 'Aviation Safety Network' sur les causes de l'accident. Ces informations prélimimaires sont basées sur les faits tel qu'ils sont connus à ce jour.
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