FAA Inspects MAX737

The Federal Aviation Administration( FAA) has final is ed a rule requiring that operators inspect Boeing 737 Max wiring shields for issues that could, in extreme circumstances, cause dual-engine failures or erroneous engine data. Flight Global reported that the rule, made public 24 June, does not relate to the flight control system implicated as a factor contributing to two 737 Maxcrashes.

The FA A’ s airworthiness directive( AD) requires that 737 Max 8 sand Max 9 s be inspected for wiring shield issues prior to flight. Both models were grounded following the crashes, and Boeing predicted that regulators would clear the jet in time to allow deliveries to resume in the third quarter. Boeing itself addressed the wire-shield issue with a service bulletin released in December 2019.

The FA A’ s order followed reports that ,“exterior fairing panel son the top of the engine nacelle and strut… may not have the quality of electrical bonding necessary to ensure adequate shielding ”.

Specifically, operators must inspect thumbnail and mid-strut fairing panels for issues with an aluminum foil that shields aircraft wiring “from the electromagnetic effects of high-intensity radiated fields ”, according to FAA documents.

Such fields are caused by “electromagnetic energy from radar, radio, television and other ground-based, ship borne or airborne radio frequency transmitters ”, according to earlier FAA materials. Those signals can affect modern aircraft that rely heavily on electric systems.

In the case of the 737 Max, “cuts” in the aluminium foil can cause electromagnetic energy to affecting wiring in ways that“could potentially lead to a dual-engine power loss event and/or display of hazardously misleading primary propulsion parameters ”, the AD says.