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FAA issues Boeing 737 MAX proposed Airworthiness Directive
4 August 2020

The FAA has issued a notice of proposed rulemaking (NPRM) for a Boeing 737 MAX airworthiness directive (AD) (PDF) as another step to clear the grounded Boeing 737 MAX jets for flight again.

The NPRM proposes mandating a number of design changes. The NPRM is open for public comments with 45 days of publication. To assist with the review of the proposed AD, the FAA also published their Preliminary Summary of the FAA’s Review of the Boeing 737 MAX (PDF).

In short, the NPRM proposes the following steps to be taken before any 737 MAX will be allowed to operate revenue flights:

  • Installation/Verification of Flight Control Computer (FCC) Operational Program Software (OPS)
    Note: Boeing updated the FCC software to eliminate MCAS reliance on a single AOA sensor signal by using both AOA sensor inputs and changing flight control laws to safeguard against MCAS activation due to a failed or erroneous AOA sensor.
  • Airplane Flight Manual (AFM) Revisions
  • Minimum Equipment List (MEL) Provisions for Inoperative Flight Control System Functions
  • Installation/Verification of MAX Display System (MDS) Software
    Note: Boeing has revised the AOA DISAGREE alert message implementation to achieve the original design intent to be standard on all 737 MAX aircraft.
  • Horizontal Stabilizer Trim Wire Bundle Routing Change
  • AOA Sensor System Test
  • Operational Readiness Flight

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