With the help of aircraft makers, the Federal Aviation Administration (FAA) often requires aircraft owners to make changes to their planes. This typically happens after a design flaw or faulty part has been discovered. To communicate the required changes the FAA publishes an Airworthiness Directive or an "AD" for short.

You can find the recent ADs listed on the FAA's web site. If you're a pilot, they make for interesting reading sometimes. I'm considering writing a scraper that'll make RSS feeds for 'em.

Anyway, this Boeing 737 AD caught my eye.

The FAA is adopting a new airworthiness directive (AD) for Boeing Model 737-300, -400, and -500 series airplanes modified in accordance with STC ST00127BO. This AD requires installation of bonding straps to the safe side harnesses of the digital transient suppression device of the fuel quantity indicating system. This AD is prompted by the results of fuel system reviews conducted by the STC holder. We are issuing this AD to prevent unsafe levels of current or energy from entering the fuel tank, due to hot short faults or threat conditions associated with the safe side harness assembly, which could result in a fire or explosion of the fuel tank.

More details in this PDF document.

It's good to know that 737 fuel tanks will be that much less likely to catch fire, isn't it? :-)

Posted by jzawodn at May 05, 2005 12:32 PM

Reader Comments
# Jeremy Leader said:

Your FAA banner link is missing a closing quote, I think.

on May 5, 2005 05:17 PM
# Jeremy Zawodny said:

Fixed. Thanks.

on May 5, 2005 06:02 PM
# Adam Dodsworth said:

Agreed but the sad thing is that the FAA does not seem able to mandate the airlines to make a lot of technical enhancements to amel;iorate problems that have been proven to have caused crashes. Taske the SR insulation related problems as a prime case - I understand that about 25% of the US airline fleets have still not made the appropriate changes. I can only conclude that the airlines have a lot of lobbying power. But nevertheless, I still feel safer in the air than on the I-80.

on May 5, 2005 11:33 PM
# wbwither said:

Heh. Didja catch this buried in the middle, under "Costs of Compliance"?

"There are about 404 airplanes of the affected design in the worldwide fleet. This AD affects about 2 airplanes of U.S. registry."

on May 6, 2005 12:33 AM
# Scott Johnson said:

2 planes isn't much, but I sure don't want to be one of the hundred or so people on one of those two planes!

on May 6, 2005 11:54 AM
# rr said:

> ... FAA does not seem able to mandate the airlines to make a lot of technical enhancements to ameliorate problems that have been proven to have caused crashes

Actually, it appears this AD is for an STC which addresses SFAR 88 compliance which was issued as a result of the TWA 800 explosion. So this is a mandated fix for a mandated fix for one of those crash-producing problems.

on May 6, 2005 04:53 PM
# said:

I'm all new to blogging, tried to do a trackback to this, but couldn't get that done somehow..

I wrote a small entry in my blog regarding the 737/747 fueltank issues...

on May 8, 2005 07:58 AM
# Chris Nolan said:

My friend Albert replied to me with the following after I sent him this link
if you follow news on aero-news.net, you'll notice ADs are released almost everyday (scary) ... [Note: They already have an RSS feed so you might want to just filter for the 'AD' ones from there?]

also read the following...

from the 737 technical site
--- scroll down to ---
Centre Fuel Tank Inerting

It's also interesting to note, this is the suspected reason for the TWA 800 accident
--- see---
Fact Sheet - FAA Airworthiness Directive on Boeing 747 Fuel Tanks

on May 8, 2005 09:54 PM
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