Frequently Asked Questions
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
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
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
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
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
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
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
Wreckage of US Air 427, near Pittsburgh,
September 8, 1994.
New AD on the 737 rudder,
Effective, November 12, 2002
Directives; Boeing Model 737 Series Airplanes
All Model 737 series airplanes; certificated in
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.
applicable changes to the adjacent systems to
accommodate the new rudder control system.
Methods of Compliance
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.
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:
only. For the full text of the New AD, go to:
New AD on the 737 rudder
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.