FAA Mandates Inspection of 2,600 737 Aircraft Over Oxygen Mask Issue

A deployed Boeing 737 NG passenger oxygen mask.
DemonDays64, CC BY 4.0, via Wikimedia Commons

The Federal Aviation Administration (FAA) has mandated inspections for over 2,600 Boeing 737 airplanes due to concerns regarding potential malfunctions with passenger oxygen masks during emergencies.

This directive arose from reports of passenger service unit (PSU) oxygen generators shifting out of their designated positions.

A displaced generator could hinder the delivery of supplemental oxygen to passengers in the event of cabin depressurization.

737 Variants: Applicability of the Directive

The inspections apply to Boeing 737 MAX and NG variants. The FAA’s airworthiness directive mandated that airlines conduct comprehensive inspections of the affected Boeing 737s.

The timeframe for these inspections varied depending on the specific aircraft model, ranging from 120 to 150 days.

Airlines were also required to take corrective actions if necessary to ensure the proper functioning of the oxygen generators.

It has been revealed that Boeing CEO Dave Calhoun will testify at a US Senate hearing on June 18.

Prior to the FAA directive, Boeing had already issued a Service Bulletin (SB) on 17 June advising airlines to perform visual inspections of the subject Boeing 737 oxygen generators.

This Service Bulletin stemmed from the discovery that a new adhesive introduced in August 2019 could, in some instances, cause the oxygen generator units to shift from their intended positions.

Consequently, Boeing reverted to using the original adhesive to address this potential safety hazard.

DemonDays64, CC BY 4.0, via Wikimedia Commons

Understanding the 737 Oxygen Generator System

Multiple parts work together to form the passenger oxygen delivery system. Here’s a breakdown of the role played by the oxygen generator:

Chemical Reaction

Unlike the crew’s oxygen system, which utilizes high-pressure gas cylinders, the passenger oxygen system relies on chemical oxygen generators. These generators contain chemicals that react when triggered, producing oxygen for the passengers.

Passenger Service Unit (PSU)

These units house the oxygen generators and are strategically located throughout the passenger cabin, typically above the seats. When a depressurization event occurs, the PSU automatically activates the oxygen generators.

Deployment and Delivery

Upon activation, the chemical reaction within the generator creates oxygen that flows through a network of tubes to the passenger oxygen masks.

The activation triggers the flow of oxygen through the tubes, delivered directly to passengers through their donned masks, aiding in proper respiration during a decompression event.

It’s important to note that these generators provide a limited duration of oxygen supply. Their primary function is to sustain passengers until the aircraft descends to a breathable altitude where normal oxygen levels are restored.

A Boeing 737 MAX aircraft on the taxiway

Public Reassurance and Transparency

The FAA mandated inspections for the subject Boeing 737 aircraft is to proactively identify and fix any problems that could prevent the oxygen generator system from functioning properly.

The system guarantees that passengers receive the necessary oxygen supply during an emergency.

Understandably, the FAA directive requiring inspections may cause some air travelers to be concerned.

However, it’s crucial to remember that these inspections are a proactive measure taken to address a potential safety issue with the oxygen masks.

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By Len Varley - Assistant Editor 4 Min Read
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