737 rudder issues resurface despite redesign

[gwillie]

I found this on Flight Global a week ago, and have been patiently waiting, expecting that it would turn up here. I'm surprised it hasn't so, what does this mean?
Not a concern?
Nobody noticed?
Hush-hush?
http://www.flightglobal.com/articles/2007/02/13/212016/737-rudder-issues-resurface-despite-redesign.html

[BOAC]

Well, its really 'just another AD', although indicative of fairly poor manufacturing errors, and the percentage of affected frames is high (681/880). However, I would not necessarily expect it to 'hit the headlines'...............unless of course it caused an accident.

The AD will require inspection/replacement within a certain time so I do not think there is a drama - yet:)

[bomarc]

what is the old saying? you can't make a silk purse out of a sow's ear?

[cfwake]

bomarc

if you mean the saying about quality, i believe the northern saying is: you can't polish a turd!!!

cf

[matkat]

Full AD
http://www.airweb.faa.gov/Regulatory_and_Guidance_Library/rgAD.nsf/0/0509AA097E77400086257275005A3828?OpenDocument

[AirRabbit]

Well, it looks to me like the article itself has already reported the determination and the conclusion .
Although Boeing identified the problem in 2006 and initiated a retrofit programme, the FAA AD and acceleration of the replacement effort was made inevitable by "the subsequent discovery of a second broken rod in December".
Boeing says 880 aircraft have been fitted with the "enhanced" rudder system, of which 681 were discovered to have been delivered with "suspect rods".
Someone, someplace is convinced that the continued operation of aircraft with the "enhanced" rudder system that was delivered with the "suspect rods," is not something that must be immediately stopped for safety considerations. I would imagine that's a difficult seat to sit in - it's a good call if nothing happens; but if one breaks and causes another hard-over rudder with resulting injuries or death - that guy would become the goat of the month!

[411A]

B737 rudder hard-overs seem to be a slight problem.
Now, never having flown the B737....I wonder if it is the same general rudder power system used on the 707.
With that aircraft, an AA 707 in 1960, a rudder hardover resulted in the loss of the airplane, and all aboard, at IDL, now JFK.
Now, on the 707 there is a rudder power switch, right over the Captains head.
Is there a similar switch on the 737?
This rudder hardover scenario was a regular training exercise in the 707 sim.
Seems to me that Boeing should have solved these 737 rudder problems a long time ago.

[vapilot2004]

Now, on the 707 there is a rudder power switch, right over the Captains head.
Is there a similar switch on the 737?


Same location but switches are for primary Flight Controls. (A & B)

I wonder if it is the same general rudder power system used on the 707.


I recall the 707 having a single hydraulic PCU. The 737 is fitted with a dual hydraulic (A & B system) PCU. The revised system has isolated A & B PCUs and a sense unit that monitors for ucommanded or jammed PCU outputs.

Boeing says 880 aircraft have been fitted with the "enhanced" rudder system, of which 681 were discovered to have been delivered with "suspect rods".

Ahh good old Flight International. Notice the items in quotations. :p

[411A]

Many thanks, vapilot2004, for the information.
Yes, as you mention, the B707 was a single PCU.
There really can't be any valid reason why Boeing hasn't fixed the rudder issues on the 737.
NOT a good scenario.:sad: :sad:

[wileydog3]

The rudder hard-over in the 737 was NOT a slight problem but the odd thing was how random it seemed to happen.

The big thing was unloading the airplane and trying to get enough speed so you were above crossover.. where you had enough aileron authority to exceed the roll being created by the rudder hardover. Pulling back increased G, increased crossover speed and decreased your chances of recovery.

It tended to be a very exciting training maneuver even in the simulator. One left with the distinct impression that while you would be able to handle it in cruise, it was not going to be a fun day and you really didn't want to have to deal with it at low pattern altitude.