Federal Express Flight 77

The first officer was the flying pilot and detected a right wing heavy condition with roll control difficulties during liftoff. The crew dumped fuel and returned for a landing. Post landing inspection showed that three of the five spoilers on top of the right wing were fully deployed. Mechanics found a general-purpose shop rag lodged in the spoiler control pulley system, jamming it in the deployed position. The pulley area where the mechanics found the rag was an open and unprotected area in the center body landing gear wheel well. The center gear doors are normally closed on the ground; however, maintenance personnel can open the doors to work in this area. The doors open and the center landing gear retracts forward into this area during normal operation. The last maintenance completed in this area was 2 days prior to the incident when a contract fuel systems repair company opened several lines in that area to check for leaks. Mechanics could not find any rags, so a supervisor brought rags from another hangar. The supervisor was positive that he provided diaper style rags rather than shop style rags. His company only used the diaper style rag because it was more absorbent than a regular shop rag. A mechanic for the carrier said they normally used colored general-purpose shop towels. They occasionally used white terrycloth towels. The airplane completed 9 flights through various line stations prior to the mishap. On a walk around inspection, mechanics do not normally open the wheel well doors and look at the spoiler pulley system.

Verbatim NTSB analysis and probable cause from the NTSB dataset