View Full Version : More mandated 737 inspections - cabin pressure switches

16th Jul 2021, 11:34
It is good to see the FAA diligence in following through a previous alert into required inspections....(Bloomberg) — More than 2,500 Boeing Co. 737 jets in the U.S. will have to be inspected after the company and regulators discovered a potential flaw in a pressure switch that could lead to pilots becoming incapacitated.

The Federal Aviation Administration said airlines and operators should inspect cabin pressure switches, which help ensure there’s sufficient air to breathe as planes climb to higher altitudes. The failure rate of the switches is “much higher than initially estimated” and poses a safety risk, the FAA said in a directive posted to the Federal Register website Thursday.


16th Jul 2021, 15:55
AD 2021-14-20 (https://public-inspection.federalregister.gov/2021-15391.pdf)

Applies to all 737 series.

16th Jul 2021, 18:06
This sort of thing is more common than most people realize - it just doesn't normally get public attention (the microscope that's being applied to the 737 presumably the reason this made headlines). Something fails more often than anticipated, or in an unanticipated manner, and the airframer realizes they need to do something about it.

Boeing recognized the issue and had already released a MOM (Multi Operator Message) recommending the actions in the AD. However the airframer does not have the power or the authority to mandate anything - that has to come from the Feds - usually in the form of an AD. It is rare that ADs don't reference an existing Service Bulletin or other airframer communication - in fact it's not particularly uncommon for the airframer to go to the Feds and request that they AD some action that the airframer has already recommended. Otherwise some operators simply won't do it.

18th Jul 2021, 01:10
Would this apply to other aircraft? This seems like an outsourced standard item.

9th Aug 2021, 11:09
If every issued AD would get an article in the news, then entire new, thick newspapers could be put out. This is news made for the sake of it - and yes, as a result of a microscopic search for 737 issues. Boeing definitely deserves whipping for putting profits above safety, but not in this way.

9th Aug 2021, 19:13

They seem to be unusually using the MOM method a lot more recently which I find a little odd; presumably the urgency took over the time needed to get the SB written up.