What is the status of the solution to the B-737 rudder design defect?  Is the problem solved?


Yes, and no.  Redesigned control units are being installed and pilots have been trained to "fly around" the problem in the interim.  But, until they completely redesign the rudder so that it is controlled by at least two separate PCUs, like other airliners, I will not be satisfied the "fix" is sufficient to prevent any possible repetitions of previous incidents/accidents. 

The Seattle Times has done an outstanding job in reporting the history of the B-737 rudder control problems.  That, plus the fact that many other papers and magazines require payment to read their articles, has led me to post links on those written by the Seattle Times, in this FAQ:  

1996 February 01:  Airlines change how 737 is landed Rudder incidents spark some to revise their flying patterns  Some U.S. airlines have begun to voluntarily change the way they fly Boeing 737s during landing approaches to give pilots a better chance of countering potential uncontrolled movements of the aircraft's rudder.

1996, March 01:  Crash panel under fire  A panel of aviation experts assigned to review investigations of the only two jetliner crashes the National Transportation Safety Board can't solve has come under fire even before it convenes.

1996, June 27:  Rudder problems ground Boeing jet  An Eastwind Airlines Boeing 737-200 has been grounded for nearly three weeks as officials investigate two recent flights disrupted by rudder problems

1996, August 23:  Close-up: FAA's 737 rules omit key change  Nine rules proposed by the Federal Aviation Administration to make the flight controls of Boeing 737 jets safer do not include a key change sought by some pilots and federal safety-board officials.

1996, October 02:  NTSB delayed introducing 737 proposals Boeing fought  Proposed safety measures for the Boeing 737 rudder did not surface publicly until 19 months after they were unveiled because Boeing argued they were unjustified. If implemented, the measures could cost the company hundreds of millions of dollars.

1996, October 27:  Safety at issue: the 737  After crashes, near-crashes and hundreds of lesser incidents, federal officials are pressing for changes in the Boeing 737, the most widely used airliner in the world.

1996, October 17:  Glossary: the 737  The vertical, hinged panel on the tail of an airplane that controls its left-to-right movement.  HARDOVER  The swift and forceful movement of an airplane's rudder as far as it can...

1996, October 28:  Safety at issue: the 737 - The crash in Colorado Springs  A debate over safety has embroiled Boeing's 737. Today, a look at questions about its rudder that grew out of a 1991 disaster; and the role Boeing takes in investigations.

1996, October 29:  Pittsburgh disaster adds to 737 doubts  A debate over safety has embroiled Boeing's 737. Today, a look at discoveries about the 737's rudder-control system and at Boeing's pressure to blame the pilots after the Pittsburgh crash two years ago.

1996, October 31:  Safety at issue: the 737 - Safety agencies struggle over 737  A debate over safety surrounds Boeing's 737. Today, the road to one federal agency's decision to recommend changes in the plane.

1996, November 02:  737 inspections ordered; Boeing cites rudder problem  Thousands of Boeing 737s will be inspected within the next 10 days for a jammed valve part that could cause a potentially dangerous uncommanded swing of the plane's tail rudder. The inspections were ordered by the Federal Aviation Administration yesterday after the Seattle-based Boeing Co. acknowledged for the first time a 737 rudder-control problem that could imperil flights.

1996, November 03:  Boeing devising limiter for 737 rudder moves  The Boeing Co. has developed a safety device to limit the movement of rudders on its 737 jetliners and may ask airlines - perhaps as soon as this week - to begin installing them on all 2,700 737s now in service.

1996, November 22:  FAA to order 737 safety changes  The Federal Aviation Administration will order U.S. airlines to train pilots of Boeing 737s how to right a 737 that is twisting out of control because of a hard, uncommanded swing of the plane's rudder.

1997, August 17:  Expert panel may have key to which 737s are most at risk  Air-safety officials are grappling with a new round of questions about whether some Boeing 737s flying today may be particularly prone to serious rudder malfunctions.

1998, June 15:  FAA to order checks of all Boeing jets  The discovery of a missing rudder-pedal fastener on a Boeing 737 and a loose pedal fastener on another - both during flight - has spurred the Federal Aviation Administration to order the inspection of 1,477 domestic Boeing passenger jets of all types.

1998, June 16:  Almost all Boeing jets to be affected by inspection order  An inspection order stemming from the in-flight discovery of missing Boeing 737 rudder-pedal fasteners will be more far-reaching than first announced, affecting all Boeing passenger jets except those models out of production.

1998, August 25:  Big airlines expect to have 737s upgraded on time  Major airlines in the United States and Europe expect to meet an Aug. 4, 1999, deadline set by the Federal Aviation Administration to install new servo valves on the rudder mechanisms...

1998, August 25:  Crash analyses point to 737 flaw  New computer simulations support a theory that rudder malfunctions could have caused the fatal spin of USAir Flight 427 into the ground near Pittsburgh four years ago, as well as loss of control in two other Boeing 737 flights.

1999, February 26:  Incidents raise questions about new rudder-control parts for 737s  Two incidents in the past week - one on the ground at Seattle-Tacoma International Airport, the other in the air over the Atlantic seaboard - have raised fresh questions about replacement rudder-control parts ordered by the FAA for Boeing 737s.

1999 March 13:  Rudder reportedly cited in 2 unsolved Boeing 737 crashes  With its staff investigators reportedly citing the rudder as the cause of two unsolved Boeing 737 crashes earlier this decade, the National Transportation Safety Board yesterday said it has no explanation yet for a fresh 737 rudder-system malfunction on the East Coast last month.

1999, March 18:  Rudder retrofitting 60 percent completed  Nearly 60 percent of the U.S. fleet of Boeing 737s now has redesigned rudder mechanisms intended to prevent a catastrophic malfunction, the Federal Aviation Administration said today.

1999, March 21:  Will hearings bring 737 crash investigation to a close?  This week, the National Transportation Safety Board will finally rule on why Capt. Germano and his co-pilot, Charles Emmett, were unable to keep USAir Flight 427 from suddenly plunging 6,000 feet in 24 seconds. The 50-ton Boeing 737 jetliner smashed explosively into a wooded ravine just outside Pittsburgh on Sept. 8, 1994, killing all 132 on board.

1999, March 25:  Analysis: NTSB's clear findings are a blow to Boeing  Short of having the National Transportation Safety Board recommend specific design changes, which some of its staff investigators had proposed, it was the worst-case outcome for Boeing....

USAIR 427 crash: ALPA's submission to the NTSB and the Addendum.

USAIR 427 crash:  NTSB Abstract of Final Report.

Wreckage of US Air 427, near Pittsburgh, September 8, 1994.

New AD on the 737 rudder, Effective, November 12, 2002

Airworthiness Directives; Boeing Model 737 Series Airplanes

Applicability: All Model 737 series airplanes; certificated in any category.

To prevent an uncommanded rudder hardover event and consequent loss of control of the airplane due to inherent failure modes, including single-jam modes, and certain latent failure or jams combined with a second failure or jam; accomplish the following:


(a) Within 6 years after the effective date of this AD, do the actions required by paragraphs (a)(1) and (a)(2) of this AD, in accordance with a method approved by the Manager, Seattle Aircraft Certification Office (ACO), FAA.

(1) Install a new rudder control system that includes new components such as an aft torque tube, hydraulic actuators, and associated control rods, and additional wiring throughout the airplane to support failure annunciation of the rudder control system in the flight deck. The system also must incorporate two separate inputs, each with an override mechanism, to two separate servo valves on the main rudder power control unit (PCU); and an input to the standby PCU that also will include an override mechanism.

(2) Make applicable changes to the adjacent systems to accommodate the new rudder control system.

Alternative Methods of Compliance

(b)(1) An alternative method of compliance or adjustment of the compliance time that provides an acceptable level of safety may be used if approved by the Manager, Seattle ACO. Operators shall submit their requests through an appropriate FAA Principal Maintenance Inspector, who may add comments and then send it to the Manager, Seattle ACO.

(2) Alternative methods of compliance, approved previously in accordance with the ADs listed in the following table, are not considered to be approved as alternative methods of compliance with this AD:

[Excerpts only.  For the full text of the New AD, go to:

New AD on the 737 rudder

Boeing Graphic of the New Redundant Rudder PCU Design


April, 2002, revised October 8, 2002

Robert J. Boser    

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The Editor of this Web Page, now retired, was an airline pilot for 33 years and holds 6 specific Captain's type-ratings on Boeing Jet Airliners.


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