EASA SIB AIR-21-12
Thrust Reverser System - Deploy / Retract Integrity Test
Summary
The Special Airworthiness Information Bulletin SAIB: AIR-21-12 is an FAA informational bulletin addressing the thrust reverser system deploy/retract integrity test on Boeing 737-600, -700, -700C, -800, -900, and -900ER series airplanes. It informs operators that after performing the integrity test required by Airworthiness Directive 2019-18-03, the thrust reversers may not deploy on the first command due to residual load. This bulletin provides additional recommendations to prevent this issue.
What Changed
This bulletin clarifies that the thrust reverser may fail to deploy on the first attempt after the integrity test due to residual torque in the locking mechanism, but will deploy on the second attempt. It introduces a recommended additional step to deploy and retract the thrust reverser after the test to release residual torque and avoid deployment failure. The bulletin does not supersede or amend AD 2019-18-03.
Why It Matters
This information is important for aviation professionals because it addresses a potential operational issue that could cause thrust reverser deployment failure on the first attempt after maintenance testing. Understanding and applying the recommended procedure helps operators and maintenance personnel avoid unexpected thrust reverser behavior, ensuring safe and reliable aircraft operation. It also aids compliance teams in managing maintenance protocols effectively.
What To Do
Operators and maintenance personnel should perform the deploy and retract cycle of the thrust reversers as specified in the Boeing 737-600/700/800/900 Aircraft Maintenance Manual Section 78-31-00, Task 'Thrust Reverser System-Adjustment/Test' after each integrity test required by AD 2019-18-03. This step should be done before releasing the aircraft for normal operation to release residual torque and prevent deployment issues. No specific compliance deadline is stated beyond performing this after each integrity test.