Unintended Effects

Corrective actions can introduce additional problems and must therefore be thoroughly evaluated by the correct disciplines and assessed for possible unintended airplane level effects. An example where corrective actions contributed to an unforeseen problem that became an unsafe condition was an event that occurred in 1983 when an Eastern Airlines airplane experienced multiple engine failures in flight due to oil leaks attributed to missing o-rings.

The L-1011 was en route from Miami International Airport to Nassau, Bahamas when the low oil pressure light for the No. 2 engine illuminated. The flight crew shut down the No. 2 engine and decided to return to Miami at which time the low oil pressure lights illuminated for the No. 1 and 3 engines followed by both engines flaming out. The flight crew restarted the No. 2 engine and made a successful single engine landing.

The investigation determined the o-rings seals had not been installed on the master chip detector (shown in the photograph on the right) for all three engines which allowed engine oil to leak and result in engine failure due to lack of oil.

The chip detectors were replaced in all three engines the previous night in accordance with a service program to address a known problem with the engine that was resulting in in-flight failures. This event is an example where the corrective actions (e.g., repetitive and frequent maintenance actions by inspecting the engine chip detectors) contributed to an unforeseen problem that became an unsafe condition. In this example, the inspection program and corrective actions to address the engine problem should have given additional consideration to potential maintenance errors and the avoidance of performing maintenance on multiple engines installed on the same aircraft at the same time. Select here to view the Special Airworthiness Information Bulletin.

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