Engine failure leads to uncommanded shutdown of PIA ATR 42-500

Casualties unknown • Karachi, PK

An engine failure on a Pakistan International Airlines flight during final approach resulted in an uncommanded in-flight shutdown of the number one engine.

What happened

On 09 June 2017, a Pakistan International Airlines (PIA) ATR 42-500, registration AP-BHM, was performing a scheduled flight from Quetta to Karachi. While the aircraft was established on the localizer for the final approach to Runway 25L at Jinnah International Airport, the pilot flying noticed a flight condition asymmetry.

Following this, the captain took control of the aircraft as several warnings appeared, including the master caution, EEC, and PEC lights for the number one engine. This was immediately followed by an uncommanded in-flight shutdown of the number 1 engine as all engine parameters unwound. The crew performed the necessary checklist actions, and the aircraft landed safely on the same approach. There were 41 passengers and 4 crew members on board; there were no injuries and no damage to the aircraft.

The investigation

The Safety Investigation Board (SIB) Pakistan conducted an investigation that included a teardown examination of the engine at the manufacturer's premises. Investigators noted that the Magnetic Chip Detector (MCD) contained heavy metal particles, and abnormal sounds and irregular movement were observed within the Accessory Gear Box (AGB).

Detailed analysis by Pratt & Whitney Canada revealed that the shutdown was triggered by the failure of bearing No. 30, which is located on the tower shaft within the AGB. The failure of this bearing caused a loss of drive from the engine, leading to the stoppage of critical driven components, including the fuel and oil pumps.

Findings

The primary cause of the in-flight shutdown was the failure of the No. 30 bearing on the tower shaft inside the AGB.
The exact mode of failure for the bearing cage could not be determined due to extensive rubbing damage on the fracture surfaces.
The Magnetic Chip Detector contained significant metal particles following the incident.
Industry data indicated a historical trend of failures related to the tower shaft and its associated bearings (No. 29 and No. 30), though such occurrences are currently decreasing.
A review of maintenance records showed that no recent maintenance had been performed by the operator specifically on the tower shaft or its bearings.

Probable cause

The engine shutdown was caused by the failure of the number 30 bearing on the accessory gear box tower shaft, which resulted in a loss of drive to essential engine components.

Frequently asked questions

What happened in the 2017-06-09 ATR 42 accident near Karachi, PK?

An engine failure on a Pakistan International Airlines flight during final approach resulted in an uncommanded in-flight shutdown of the number one engine.

What aircraft was involved and where did it happen?

The accident on 2017-06-09 involved a ATR 42, registration AP-BHM, operated by PIA, at Karachi, PK.

What was the probable cause of the accident?