The Taiwan Transportation Safety Board (TTSB) releases final report on the investigation of a Far Eastern Air Transport (FAT) flight FE8026 aircraft left engine failure at about 10 miles from Taipei/Songshan (Songshan) Airport during final approach phase.

On July 2, 2018, a FAT MD-82 scheduled passenger aircraft, flight number FE8026, registration number B-28035, departed from Penghu Airport to Songshan Airport, with 2 flight crew, 4 cabin crew and 165 passengers, totally 171 people on board. The flight crew declared a “pan-pan” during final approach phase at 9.6 nautical miles away from the runway 28 threshold of Songshan Airport, the aircraft landed safely at the Songshan Airport. The on board persons were all safe.

According to the Transportation Occurrence Investigation Act of the Republic of China, and referring to Annex 13 to the Convention on International Civil Aviation, the TTSB, an independent transportation occurrence investigation agency, started the investigation. The organization or agency been invited to join the investigation team included: National Transportation Safety Board, United States, Pratt & Whitney Company, United States, Civil Aeronautics Administration, Ministry of Transportation and Communications (CAA) and FAT. The Final Report was reviewed and approved by TTSB’s 5th Board Meeting on November 1, 2019.

Findings related to probable causes:

1. One of the 58 Low Pressure Turbine 4th stage (LPT4) blades on left engine of occurrence aircraft was fractured due to high cycle fatigue, the fracture occurred before its next scheduled check time is due, which was after performed an Airworthiness Directive (AD) check per CAA-2011-03-013 requested, the blade did not reach its designed initial check schedule when the blade fractured either. The fractured blade caused the fall-off of 5 segments of the LPT4 stator blades, the displacement of No. 6 bearing and the fracture of the other 57 LPT4 blades, and resulted in an uncontained engine failure by the fractured blades penetrated through the turbine fan bypass case and engine cowling.

Findings related to risk:

1. In the past 3 times of LPT4 shroud notch wearing checks, there were twice that FAT maintenance personnel did not in compliance with AD CAA-2011-03-013 requested to be performed with engine on-wing condition.
2. There was no manufacturing serial number of LPT4 blade on the occurrence engine for maintenance control, and no traceable historical records with total time usage since new either.

Safety Recommendations

To Far Eastern Air Transport:

1. Perform Low Pressure Turbine (LPT) blade torque check per CAA AD 2011-03-13 and the post-occurrence requests by CAA, and performs the LPT blade check in accordance with CAA’s requests per the latest revision of Pratt & Whitney’s (P&W) ASB A6224 R7.

To Civil Aeronautics Administration, Ministry of Transportation and Communications:

1. Supervise FAT to perform LPT blade torque check per CAA AD 2011-03-13 and the post-occurrence requests by CAA, and supervise FAT to perform the LPT blade check by following the revised time interval as per the latest revision of P&W’s ASB A6224 R7.
2. Request FAT to draft a concrete and feasible monitoring and control method for the hot section parts without manufacturing serial number or incomplete historical documents of the occurrence engine model, and continuous monitoring the usage of occurrence engine model in FAT.

To Pratt & Whitney Company:

1. Despite the revision of the latest ASB A6224 with more restricted inspection criteria and interval on JT8D engine LPT4 blade in third quarter, 2019, P&W still ought to continuously watch global operation conditions of the occurrence engine model. Revise relevant inspection criteria to avoid the occurrence of uncontained engine failure by the fractured LPT blades.

The final report is in Chinese only and available for download at https://www.ttsb.gov.tw

Sherry Liu, Safety Investigator
Tel: 89127388-6286
Email:sherry@ttsb.gov.tw
Website: https://www.ttsb.gov.tw