scope:

Abstract:

On 4 April 2005, during a routine double engine removal operation on a F-15B, tail number 836, at NASA Dryden, the aircraft center of gravity shifted forward, compressing the nose gear strut, and the right engine inlet contacted a crew entry/maintenance stand.

The first engine removal was started at 0630 with a crew briefing concerning the engine removal. The crew consisted of 4 NASA mechanics. Only one crew member had done the task within the past year, all others were either new to the aircraft or had not performed an engine removal in the past year. More than one member of the crew verified that the crew entry stand was clear of the aircraft before starting the task. The first engine removal was nominal until the engine was being rolled back on the engine removal trailer, when some difficulty was experienced due to corroded rollers (a standard Air Force 4000 trailer).

After the first engine was pushed back from the F-15B and was being transferred onto the transportation dolly (a standard Air Force 3000 trailer), a NASA technician assigned to the F-15B conducted a tour of the aircraft. He briefed the crew chief and lead technician that morning prior to conducting the tour and was given an OK. He did use the crew maintenance stand, and verified that the stand was clear of the aircraft.

Due to the time involved with the first engine removal, the second was not started until after lunch (approximately 1330). The crew assumed that all equipment was still clear of the aircraft and proceeded to remove the second engine. The removal was nominal as was the transfer this time due to repairs made to the trailer. After the engine was removed and the trailer disconnected from the aircraft, the aircraft experienced a CG shift transferring weight forward on the F-15B, this is a normal occurrence when both engines are removed.

At approximately 1430, the aircraft was being secured for maintenance and a NASA avionics/ instrumentation technician (who was not involved with the engine removal, but assigned to the F- 15B) went to remove the canopy strut, close the canopy and move the crew maintenance stand. When he went to remove the stand, he could not pull it away from the aircraft. Upon further inspection, he found the right engine inlet resting on the stand. He then contacted the crew chief and they placed a nose jack under the F-15B, raising the aircraft high enough to remove the stand. No one was injured in this incident.

The damage consisted of approximately 1.5" by 1.5" L-shaped deformation to the edge of the engine inlet. After inspection, no other damage was found.

It was determined that the primary factor for the incident was the lack of proper aircraft area inspection when the second engine removal was started. Other contributing factors were that the stand could have been designed to prevent this situation and wasn't, and the use of additional safety equipment (nose jack) is always an option to the task leader, even if the written procedures do not call for it.

In addition, integrity of the incident scene is important. The aircraft should have been jacked up to stabilize it, but the stand left in place and photo called to document the incident.