Civil Aviation Administration

Statens Luftfartsvæsen

AIS HQ / Luftfartsinformationstjenesten, Ellebjergvej 50, DK-2450 København SV, Danmark

TEL: +45 36 18 60 00, FAX: +45 36 18 60 22, E-mail: ais@slv.dk, Internet: www.slv.dk/publikationer

01 / 03

3 JAN

AIC B-01 / 03. Use of Rudder on Large Transport Aeroplanes:

Introduction.

As a result of the A300-600 accident at New York on 12 Novem-

ber 2001, the National Transportation Safety Board (NTSB) of

the USA recommended further guidance for pilots on the use of

rudder and the structural implications of inappropriate use of

controls.

The engineering design and airworthiness requirements ensure

that the aircraft is capable of withstanding the rapid application

of full rudder from the neutral position in one direction and the re-

turn to neutral from a large sideslip angel. A further safety factor

over and above the design load is then applied. However, aircraft

are not designed to withstand application of large rudder angels

opposite to that required to sustain the sideslip. This may occur

when, for example, full rudder is applied in one direction followed

by full application in opposite direction. Such a manoeuvre may

result in structural failure.

Pilots should be aware that the pedal force required to obtain

rudder deflection will vary according to airspeed and the design

of any rudder limiter system. The effect of this may be that full

rudder application is obtainable at relatively low pedal force at

high speed. It is also important to use the rudder in a manner that

avoids unintended large sideswipe angels and resulting exces-

sive roll rates. The amount of roll that is generated is typically

proportional to the amount of sideslip, and to the amount of rud-

der input.

Handling Considerations.

The rudder is suitable for use in event of an engine failure and

for crosswind take-offs and landings. The use of full rudder in

these situations is well within structural limitations and pilots

should not be inhibited from applying the necessary rudder input

for satisfactory control of the aircraft. The aircraft will have been

designed to accommodate a rapid and immediate pedal input in

one direction from zero to full input, e.g. during an engine failure

during take-off. There has been no known catastrophic failure

due to pilot control input in these situations.

With the possible exception of wake turbulence encounters and

an upset recovery, the use of rudder in other situations, including

stall recovery is not necessary and should not be used unless

specifically recommended in the Aircraft Flight Manual. Recovery

from dutch roll, which normally occurs at high level, should be in

accordance with the manufacturers guidance, typically using ai-

leron as the primary control surface. Due regard should be taken

of any limitation or operational restrictions contained in the Min-

imum Equipment List (MEL) in the event of yaw dampers being

inoperative.

As the aircraft flies faster, less rudder authority is required. Pilots

should ensure that they are familiar with rudder limiting system

fitted to the aircraft.

Conclusion.

Whilst pilots should not be inhibited from using the necessary

rudder input for asymmetric and crosswind control, sudden re-

versals of rudder should be avoided.

Training

The Danish CAA recommends the operators of transport-catego-

ry airplanes to establish and implement pilot training programs

that: (1) explain the structural certification requirements for the

rudder and vertical stabilizer on transport category airplanes; (2)

explain that a full or nearly full rudder deflection in one direction

followed by a full or nearly full rudder deflection in opposite direc-

tion, or certain combinations of sideslip angels and opposite rud-

der deflection can result in potentially dangerous loads on the

vertical stabilizer, even at speeds below the designed manoeu-

vering speed; and (3) explain that, on some aircraft, as speed in-

creases, the maximum available rudder deflection can be

obtained with comparatively light pedal forces and small pedal

deflexions. In addition the operator should ensure that this train-

ing does not compromise the substance or effectiveness of ex-

isting training regarding proper rudder use, such as during

engine failure shortly after takeoff or during strong or gusty

crosswind takeoffs or landings.

(TO)