[70-80发动机CFM56-7] 关于737NG发动机后下部的反推整流罩对齐标记

One operator has reported that their 737-600/-700/-800/-900 airplanes have maintenance write-ups for the thrust reverser translating sleeve witness marks not being aligned or missing. This has caused delays and resulted in thrust reversers being deactivated per the Minimum Equipment List (MEL).

The purpose of the witness marks are for visual verification that the thrust reverser sleeves are stowed and locked. If the witness marks are not aligned, the thrust reverser may not have stowed properly after thrust reverser operation. The marks are for the benefit of the pilot's walk around spanflight inspection.

The witness marks should not be used as the sole indication that the thrust reverser is in the locked position and rigged properly. The flight deck indications define the state of the reverser sleeves and should be used for thrust reverser position indication. The witness marks can be used for visual verification of thrust reverser position but final verification should be based on flight deck indication.

If the witness marks do not align after hydraulic spanssure is applied and there is no flight deck indication pertaining to the thrust reverser position, the thrust reverser is not required to be deactivated. The flight deck indications define the state of the thrust reverser position.

If the witness marks are missing, the thrust reverser is satisfactory for continued service provided there are no flight deck indications pertaining to the thrust reverser. If desired, the witness marks can be reapplied to the thrust reverser per the reference AMM task.

The witness marks are added to the reverser during aircraft production by the Exterior Marking - Maintenance drawing (414A4970 Sheet 7) and are considered maintenance aids which are not required for dispatch of the airplane. The witness marks can be deleted at the operators discretion.