777 Airworthiness Directive to be issued

You have to love the FAA. There is an Airworthiness Directive being issued for all Boeing 777s, to inspect and possibly replace the dual pitch rate sensors. There are reports that both sensors failed on some aircraft, which disconnects the autopilot and autoland system. At low altitude, this could create a problem if the crew isn't able to react in time for a go around, or manual landing.

The AD gives operators 60 months to inspect and change all four sensors, part number 402875-05-01.

I always love when the FAA issues an AD like this, and then gives the airlines years to complete them. I understand they don't want to cause the airlines to lose too much money, but some of these are a joke. The AD for 747 cargo doors after United 811 is a prime example. The cargo door opened in flight on that aircraft, due to a faulty locking mechanism. They came up with a fix, and then gave the airlines something like two years to implement the fix, so they didn't lose money.

Granted this one isn't as big an issue as that, but still, five years is an incredible amount of time to give them to perform it.

A new airworthiness directive issued by the US Federal Aviation Administration requires Boeing 777 operators to inspect and potentially replace the aircraft's dual pitch rate sensors (PRS).

The directive, which applies to 777-200LRs, -300s, -300ERs and 777 freighters, comes in response to reports received by the agency of dual failures of the sensors.

When both sensors fail, the aircraft's primary flight computer transitions from primary to secondary mode, which causes the autopilot to disengage, says the directive, made public by the US Office of the Federal Register on 19 November.

"We are issuing this AD to prevent a dual PRS failure that could cause an automatic disengagement of the autopilot and autoland," says the DOT's directive.

www.flightglobal.com...

a reply to: Zaphod58

Ya know what's funny? I knew that it was you posting this before I opened it - and I failed to read the subtitle that probably has your name in it...

#Zaphod4Lief

K.

I couldn't agree more with you that it's a little absurd that they give so much turnaround time on Airline related issues like this.

Take a look at the Car recalls going on right now - how long did They have to fix the problem? How much more money was involved?

Airlines might as well be a public service at this point - at least you would think they are based on the bureaucracy and 'nepotism' ( if you will ) involved.

Good post Zaphod; Glad they're fixing it - but I would expect a quicker turnaround for something like this myself.

@ Zaphod

@ The timeline

a reply to: Zaphod58

AD's are given time for implementation based upon the risk and potential failure rate - where there is an immediate safety implication it is entirely possible to have an AD that requires action before further flight.

In this instance there have been a small number of events over 100's of 1,000's of hours of operation, the failure does not constitute an immediate danger to the aircraft (it can continue to fly quite safely) except possibly during landing - and that possibility can be covered by procedural changes.

Here is the full text of the final AD wording

a reply to: Aloysius the Gaul

Except I've seen major safety of flight issues get a year and a half plus to be implemented. I don't expect groundings, certainly I can see giving time for something like this, but some of the timelines are insane.

a reply to: Zaphod58
In my experience I totally agree with you Zaphod. There seems to be a commercial imperative that sometimes drives AD's. Its understandable to a point, crack down too hard or too quick and you have the dual problems of organisations not being able to react quickly enough in the real world across a possibly large and dispersed fleet , as well as it being financially backbreaking that can cause industry chaos. However the delay in some of these AD's given their seriousness defies explanation while others that are far less serious are actioned more quickly, frankly I too don't get it.

Case in point is the infamous TWA 800 flight that allegedly exploded in 1996 possibly due to a Centre Wing Tank (CWT) fuel probe wiring harness arcing in a near empty tank (the actual source has never been identified). I personally worked on the very first commercial installation of a solution to the problem in the aircraft type that eventually brought this about (747), namely a nitrogen inerting system. But despite conclusions being drawn very early around 2000 and tests of a solution in 2004 by the FAA and NASA it took until around Sept/Oct 2010 before the first On-Board Inert Gas Generation System (OBIGGS) was fitted to that 747 I worked on. And bear in mind that the FAA had proposed a final rule on the issue in 2005, issued it in 2008, and admitted that it had recorded four such incidents in the previous 16 years with a known case of fuel tank compensator arcing in a 747 as far back as 1976.

LEE.

a reply to: Zaphod58

Presumably your assessment of "major" differs from the FAA's.

I've been part of the AD process in another country as a risk assessor - immediate risks get immediate action. Lesser risks get time to be implemented - the exposure and consequences are closely examined when determining time frames.

a reply to: Aloysius the Gaul

I'd consider cargo doors opening in flight pretty major, yet they got years to correct it, because it would have "caused undue hardship to the airlines" to order an immediate fix.