NTSB urges Boeing 757 Engine Inspections

Air Safety Week, Oct 27, 2008

Delta Air Lines will inspect the Pratt & Whitney PW2037 engines on its 132 Boeing 757 jetliners after one engine failed and another on an American Airlines plane developed cracks.

The National Transportation Safety Board (NTSB) has asked the Federal Aviation Administration (FAA) to order the inspections, citing "serious concerns that warrant immediate action by the FAA." A decision is pending.

A Delta spokeswoman said Delta will inspect its planes during scheduled maintenance, rather than pulling the planes out of service to do the checks.

The PW2037 engine powers 725 Boeing 757 jetliners, according to Pratt & Whitney.

The NTSB began examining the engines after Delta pilots heard a bang and lost engine power during the takeoff roll at the Las Vegas airport on Aug. 6. The plane returned to the parking area and no one was hurt.

The Safety Board, in a letter to the FAA seeking the inspections, citing concerns that pieces of the engine could penetrate fuel tanks, causing a leak and fire.

"Information gathered to date has raised serious concerns that warrant immediate action by the FAA," the safety board wrote Robert Sturgell, the FAA's acting administrator.

The letter recommends that the FAA take action to address the safety issue concerning uncontained engine failures as a result of cracking in the 2nd stage turbine hub blade retaining lugs on PW2037 engines.

The Safety Board said it has learned that at least four other PW2037 2nd stage turbine hubs have had cracks in the blade retaining lugs, but been unable to obtain specific details about these four PW2037 2nd stage turbine hubs because P&W, despite being a party to this investigation, has not yet responded to the Board's requests for information about these hubs.

"The Safety Board is concerned about the risk of uncontained failures in high time

PW2037 engines, such as the Delta Air Lines and American Airlines engines, that have not had inspections of the 2nd stage turbine blade roots for uneven wear.

"The Safety Board concludes that the serious nature of these two independent potential failure modes, which could cause future uncontained engine failures, requires timely action to address the hazard until the cause of the failures can be determined and appropriate action can be taken to prevent a recurrence. Therefore, the Safety Board believes that the FAA should require that P&W PW2037 engines be removed from service for inspection of the 2nd stage turbine hubs when they have accumulated significantly fewer hours and/or cycles than the incident engine (10,880 hours and/or 4,392 cycles).

"The Safety Board further concludes that the risk of future uncontained 2nd stage turbine hub failures in PW2037 engines will not be eliminated with only a one-time inspection. Therefore, the Safety Board believes that the FAA should require that PW2037 2nd stage turbine hubs undergo recurring inspections when they have accumulated significantly fewer hours and/or cycles than the incident engine (10,880 hours and/or 4,392 cycles) until the cause for the previous instances of cracking is identified and corrective action to prevent future cracking is implemented," the letter stated.

[Copyright 2006 Access Intelligence, LLC. All rights reserved.]