Airworthiness Directive · Amendment 39-19730 · Exhaust
The Boeing Company Airplanes
This AD applies to all The Boeing Company Model 737 series airplanes, certificated in any category, excluding Model 737-100, -200, -200C, -300, -400, and -500 series airplanes.
The FAA is adopting a new airworthiness directive (AD) for all The Boeing Company Model 737 series airplanes, excluding Model 737-100, -200, -200C, -300, -400, and -500 series airplanes. This AD requires revising the existing maintenance or inspection program to remove text that allows the size of the thrust reverser upper locking actuator lock sensor target to be changed, and, for certain airplanes, performing repetitive integrity tests of the thrust reverser upper locking actuator. This AD was prompted by a report indicating that alteration of thrust reverser upper locking actuators in accordance with certain data in the Boeing aircraft maintenance manual (AMM) could delay or prevent detection of the failure of the locking mechanism of a thrust reverser upper locking actuator. The FAA is issuing this AD to address the unsafe condition on these products.
For all airplanes: Within 30 days after the effective date of this AD, revise the existing maintenance or inspection program, as applicable, by removing any steps that change the size of the thrust reverser upper locking actuator lock sensor target.
For all airplanes: As of the effective date of this AD, no person may alter the thrust reverser upper locking actuator lock sensor target by grinding or trimming or otherwise removing material from the lock sensor target.
For Model 737-600, -700, -700C, -800, -900, and -900ER series airplanes: Within 90 days after the effective date of this AD, conduct an integrity test of the thrust reverser upper locking actuator on all 4 locking actuators on the airplane. The integrity test must include at least the steps specified in figure 1 to paragraphs (i) and (k) of this AD. The integrity test is not required to be completed for all 4 actuators in one maintenance visit, provided all 4 actuators are tested within the compliance times specified in this paragraph. During the test, a slight movement from fully stowed on the lower portion of the thrust reverser is acceptable due to the wind up in the flexible shafts between the synchronization lock and the upper actuator lock.
Note 1 to paragraph (i): Additional guidance for the integrity test can be found in Boeing 737 AMM Task 78-31-03.
After the initial integrity test required by paragraph (i) of this AD, repeat the test thereafter at intervals not to exceed 750 flight hours.
If, during any integrity test required by paragraph (i) or (j) of this AD, the movement of the thrust reverser exceeds the acceptable “slight movement” described in paragraph (i) of this AD, replace the locking actuator before further flight.
