Another 737 rudder incident
 

NTSB Investigates Boeing 737 Rudder

By DENNIS CONRAD, Associated Press Writer

WASHINGTON (AP) - The National Transportation Safety Board is investigating whether a rudder problem caused a United Airlines Boeing 737 to suddenly bank while descending for a landing in Chicago last week. The plane landed safely.

Rudder problems on 737s are suspected in two deadly U.S. air crashes in the early 1990s. Last month, the Federal Aviation Administration proposed requiring airlines to install new rudder control systems on 737s, the world's most popular commercial jets.

The rudder is the flap on the vertical tail of the aircraft. Moving the rudder left or right causes the plane to turn in that direction.

The pilots flying United Airlines Flight 578 from St. Louis to Chicago's O'Hare International Airport last Thursday afternoon reported the plane's nose suddenly swung to the left and right when the aircraft began descending at around 9,000 feet, FAA spokesman Paul Turk said Monday.

The pilots disconnected the autopilot and the plane then banked sharply, Turk said. They had to apply pressure on the rudder pedals to level the wings and regain control.

After the plane touched down, the pilots said the rudder swung left and then fully to the right, causing a loud bang, Turk said.

The plane stopped safely and all 93 passengers got off without incident.

NTSB spokeswoman Lauren Peduzzi said investigators checked the plane during the weekend and are studying its flight data recorder and cockpit voice recorder.

"We're still reviewing all the data to see exactly what caused the incident,'' said Peduzzi, who described it as a "rudder anomaly.''

Boeing spokeswoman Liz Verdier said a number of factors could have been responsible, including the aircraft itself, the pilot or the weather.

"We don't know what that anomaly is,'' she said.

Verdier said Boeing considers the incident serious and would consider checking its entire fleet if the NTSB investigation indicates it could be more than an isolated occurrence.

United spokesman Joe Hopkins declined to comment.

Boeing announced in September that it would train pilots in how to handle jammed rudders and would begin installing new rudder systems on 737s in 2003.

The FAA's rudder proposal would give the airlines five years to install the new systems. The FAA estimates that 2,000 U.S. airplanes would have to be refitted, at a cost of $364 million.

The FAA is seeking public comments for 60 days before issuing the new directive.

The NTSB blamed rudder problems for a US Airways crash outside of Pittsburgh in 1994 that killed 132 people and a United Airlines crash at Colorado Springs, Colo., in 1991 that killed 25.

My, my! These journalists shouldn't try to explain aviation terms in their own words. It only comes out worse.

And of course they had to mention the possibility of it being the pilot at fault. Some things never change (and never will).

It probably was the yaw damper acting up.

Uncommanded Yaw or Roll Checklist:

1. Maintain Aircraft Control With All Available Flight Controls.
2. Increase Airspeed And Reduce AOA (if required).
3. Autopilot (if engaged)...Disengage.
4. Yaw Damper...Off.

knackered,

I understand why the professional users (I'm just SLF with an interest in the industry) of PPRUNE castigate journalists from time to time, but in this case the writer was quoting a Boeing spokesperson. Would you expect them to censor the quote?

Meering

Knackerd.
I agree with you that 'Control Surface' may have been a better term but I guess 'flap' will do for the general public don't you think? Second, as far as I can make out from the above it was Liz Verdier, a Boeing Spokeswoman who mentioned Pilot Error -however unlikely that is. Nevertheless, I hope that we won't leave any avenue unexplored to explain this upset though.
What concerns me more is that this may be yet another example of a 737 with a rudder problem. How many more are there that have been diagnosed as Yaw damper problems? Boeing are only starting in [b]2003[\b] to install a modified rudder control system when it is known (suspected??) that there are problems?

Cheers

hicks

[ 18 December 2001: Message edited by: Hicks ]

was this the 100/200 or 300 onwards, anybody know?
Well done to the crew, could have been accident no 3.

Looks like a classic case of wake turbulence from here .... :p

Wake turbulence at 9000' in the descent? Wake up!

This will probably turn out to be yet another "unexplained" rudder hard over from the B737. However, of course, Boeing have had a really good look at them and nothing is wrong. So why then have they re-designed for the NG and the FAA ordered reengineering all B7373 in service?

If it was wake turbulence, why the bang and swing soem time later after touchdown.

How does Boeing get away with this kind of thing?

[ 18 December 2001: Message edited by: moggie ]

I've had a B737-300 roll through > 45° on me - twice !

First time, we were following a B747, and the second time was behind a A321 - but both times were during the descent (former at 12,000' on the way into STN, the later just as we were joining the localiser into CPH)

QRH drill actioned accordingly - and not really a problem.

was this the 100/200 or 300 onwards

United 200s are retired. Only have -300s and -500s now.

Any other industry source for this news?

Thanks.

Meering,

As I read the above article, the reference to 'flap' was not part of the Boeing quote.

Hicks,

'Control surface' would have been a better term, yes, but I don't agree that 'flap' will suffice. We often complain of the public's perception of things aviation but if we are going to feed them rubbish then what?

I didn't mean to imply that the reporter was implying possible pilot error. The 'they' I refer are the usual industry spokesmen, in this case Boeing, who find it convenient to keep the old 'pilot error' cause as a standby always.

Anyway, this is a side issue to the main thread here, but these issues always come up with these type of reports and I find it unnecessary and misleading.

Moggie

'Wake turbulence at 9000' in the descent? Wake up!'

You obviously have no experience of commercial flight operations or you would know its possible to encounter another aircraft's wake anywhere at any stage of flight. :D

Hey Puritan, somebody been letting you practice your hand flying?! :p G'luck mate.

There has also been a problem with the tail (rudder?) of a Transavia 737 towards the end of 96 or early 97, I believe when landing at FRA; this was shortly after the aircraft came back from check at TAP.

Can anyone shed any light on this incident/accident, and clarify whether it was the same class of problem as the one discussed on this thread or whether it was a different one?

quote ....

The FAA's rudder proposal would give the airlines five years to install the new systems. The FAA estimates that 2,000 U.S. airplanes would have to be refitted, at a cost of $364 million. ..... end quote

364 million divided by 2000 aircraft = 182,000 dollars each ..... now lets say that a 737 might fly an average of 300 days per year at 600 passengers per day .... thats equal to 180,000 passengers per year ..... could we please all give the airline that we are flying, an extra dollar each trip and solve this problem now!!!!

(if my passenger load estimates are low then let the airlines send any excess in the one dollar charge to charity)

spelling corrected .....

[ 18 December 2001: Message edited by: hobie ]

Montt

So far as I remember this was an mx problem in that a bolt had not been fastened correctly during the checks and the nut unwound. Brilliant flying by the crew saved the day. Never did hear what happened to the TAP maintenance people. Probably the lawyers were the only ones who gained anything.

Knackered

Very true.

Cheers

hicks

Boeing 737 Problem Investigated
By DENNIS CONRAD, Associated Press Writer

WASHINGTON (AP) - Federal investigators are looking at whether a wire brush left under the cockpit floor of a United Airlines Boeing 737 led to a rudder problem that caused the plane to suddenly bank while descending into Chicago last week.

United Airlines spokesman Chris Brathwaite confirmed the brush was found in the cockpit area but declined to say how it got there.

He said the company is cooperating with investigators to determine whether the brush caused the problem on the Dec. 13 flight from St. Louis to Chicago's O'Hare International Airport.

The Air Line Pilots Association, which also is looking into the matter, believes the brush was left behind by a mechanic and jammed the rudder cables, spokesman John Mazor told The Seattle Times.

National Transportation Safety Board spokesman Paul Schlamm said investigators have not drawn any conclusions.

"The investigation is still continuing on many fronts,'' he said Thursday.

The pilots flying United's Flight 578 reported the plane's nose suddenly swung to the left and right when the aircraft began descending at around 9,000 feet. The pilots disconnected the autopilot and the plane then banked sharply. They had to apply pressure on the rudder pedals to level the wings and regain control.

The plane landed safely and all 93 passengers got off without incident.

The rudder is the flap on the vertical tail of the aircraft. Moving the rudder left or right causes the plane to turn in that direction.

Rudder problems on 737s are suspected in two deadly U.S. air crashes in the early 1990s. Last month, the Federal Aviation Administration proposed requiring airlines to install new rudder control systems on 737s, the world's most popular commercial jet.

I hope the FAA doesn't try to brush this one off . . .