[Federal Register Volume 62, Number 1 (Thursday, January 2, 1997)]
[Rules and Regulations]
[Pages 15-16]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 96-33104]


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DEPARTMENT OF TRANSPORTATION
14 CFR Part 39

[Docket No. 96-NM-266-AD; Amendment 39-9871; AD 96-26-07]
RIN 2120-AA64


Airworthiness Directives; Boeing Model 737 Series Airplanes

AGENCY: Federal Aviation Administration, DOT.

ACTION: Final rule; request for comments.

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SUMMARY: This amendment adopts a new airworthiness directive (AD) that 
is applicable to all Boeing Model 737 series airplanes. This action 
requires revising the FAA-approved Airplane Flight Manual (AFM) to 
include procedures that will enable the flight crew to take appropriate 
action to maintain control of the airplane during an uncommanded yaw or 
roll condition, and to correct a jammed or restricted flight control 
condition. This amendment is prompted by an FAA determination that such 
procedures currently are not defined adequately in the AFM for these 
airplanes. The actions specified in this AD are intended to ensure that 
the flight crew is advised of the potential hazard associated with a 
jammed or restricted flight control condition and of the procedures 
necessary to address it.

DATES: Effective January 17, 1997.
    Comments for inclusion in the Rules Docket must be received on or 
before March 3, 1997.

ADDRESSES: Submit comments in triplicate to the Federal Aviation 
Administration (FAA), Transport Airplane Directorate, ANM-103, 
Attention: Rules Docket No. 96-NM-266-AD, 1601 Lind Avenue, SW., 
Renton, Washington 98055-4056.
    The information concerning this amendment may be obtained from or 
examined at the FAA, Transport Airplane Directorate, 1601 Lind Avenue, 
SW., Renton, Washington.

FOR FURTHER INFORMATION CONTACT: Les Berven, Flight Test Pilot, Flight 
Test Branch, ANM-160S, Seattle Aircraft Certification Office, FAA, 
Transport Airplane Directorate, 1601 Lind Avenue, SW., Renton, 
Washington 98055-4056; telephone (206) 227-2666; fax (206) 227-1181.

SUPPLEMENTARY INFORMATION: As part of its Continuing Operational Safety 
Program, the FAA has become aware of new information related to the 
safety of Boeing Model 737 series airplanes. Recent tests of the main 
rudder power control unit (PCU), conducted at Boeing, demonstrated a 
potential failure scenario that was previously unknown. These tests 
revealed that, if the secondary slide of the PCU jams in certain 
positions, rudder pedal input can cause deformation in the linkage 
leading to the primary and secondary slides of the servo valve of the 
main rudder PCU. This situation could result in rudder deflection in 
the opposite direction of the rudder command, and a jammed rudder.

Other Relevant Rulemaking

    The conditions described previously were addressed previously in AD 
96-23-51, amendment 39-9818 (61 FR 59317, November 22, 1996), which is 
applicable to all Boeing Model 737 series airplanes. That AD requires 
repetitive tests to verify proper operation of the rudder power control 
unit (PCU), and replacement of the PCU, if necessary. The actions 
specified by that AD are intended to prevent rudder motion in the 
opposite direction of the rudder command.

FAA's Findings

    As a result of analysis related to the previously prescribed tests, 
the FAA finds that certain procedures should be included in the FAA-
approved Airplane Flight Manual (AFM) for Model 737 series airplanes to 
enable the flight crew to take appropriate action to maintain control 
of the airplane during an uncommanded yaw or roll condition, and to 
correct a jammed or restricted flight control condition. The FAA has 
determined that such procedures currently are not defined adequately in 
the AFM for these airplanes.

Explanation of the Requirements of the Rule

    Since an unsafe condition has been identified that is likely to 
exist or develop on other Boeing Model 737 series airplanes of the same 
type design, this AD is being issued to ensure that the flight crew is 
advised of the potential hazard associated with a jammed or restricted 
flight control condition and of the procedures necessary to address it. 
This AD requires revising the AFM to include procedures that will 
enable the flight crew to take appropriate action to maintain control 
of the airplane during an uncommanded yaw or roll condition, and to 
correct a jammed or restricted flight control condition.

Determination of Rule's Effective Date

    Since a situation exists that requires the immediate adoption of 
this regulation, it is found that notice and opportunity for prior 
public comment hereon are impracticable, and that good cause exists for 
making this amendment effective in less than 30 days.

Comments Invited

    Although this action is in the form of a final rule that involves 
requirements affecting flight safety and, thus, was not preceded by 
notice and an opportunity for public comment, comments are invited on 
this rule. Interested persons are invited to comment on this rule by 
submitting such written data, views, or arguments as they may desire. 
Communications shall identify the Rules Docket number and be submitted 
in triplicate to the address specified under the caption ADDRESSES. All 
communications received on or before the closing date for comments will 
be considered, and this rule may be amended in light of the comments 
received. Factual information that supports the commenter's ideas and 
suggestions is extremely helpful in evaluating the effectiveness of the 
AD action and determining whether additional rulemaking action would be 
needed.
    Comments are specifically invited on the overall regulatory, 
economic, environmental, and energy aspects of the rule that might 
suggest a need to modify the rule. All comments submitted will be 
available, both before and after the closing date for comments, in the 
Rules Docket for examination by interested persons. A report that 
summarizes each FAA-public contact concerned with the substance of this 
AD will be filed in the Rules Docket.
    Commenters wishing the FAA to acknowledge receipt of their comments 
submitted in response to this rule must submit a self-addressed, 
stamped postcard on which the following statement is made: ``Comments 
to Docket Number 96-NM-266-AD.'' The postcard will be date stamped and 
returned to the commenter.

Regulatory Impact

    The regulations adopted herein will not have substantial direct 
effects on the States, on the relationship between the national 
government and the States, or on the distribution of power and 
responsibilities among the various levels of government. Therefore, in 
accordance with Executive Order 12612, it is determined that this final 
rule does

[[Page 16]]

not have sufficient federalism implications to warrant the preparation 
of a Federalism Assessment.
    The FAA has determined that this regulation is an emergency 
regulation that must be issued immediately to correct an unsafe 
condition in aircraft, and that it is not a ``significant regulatory 
action'' under Executive Order 12866. It has been determined further 
that this action involves an emergency regulation under DOT Regulatory 
Policies and Procedures (44 FR 11034, February 26, 1979). If it is 
determined that this emergency regulation otherwise would be 
significant under DOT Regulatory Policies and Procedures, a final 
regulatory evaluation will be prepared and placed in the Rules Docket. 
A copy of it, if filed, may be obtained from the Rules Docket at the 
location provided under the caption ADDRESSES.

List of Subjects in 14 CFR Part 39

    Air transportation, Aircraft, Aviation safety, Safety.

Adoption of the Amendment

    Accordingly, pursuant to the authority delegated to me by the 
Administrator, the Federal Aviation Administration amends part 39 of 
the Federal Aviation Regulations (14 CFR part 39) as follows:

PART 39--AIRWORTHINESS DIRECTIVES

    1. The authority citation for part 39 continues to read as follows:

    Authority: 49 U.S.C. 106(g), 40113, 44701.


Sec. 39.13  [Amended]

    2. Section 39.13 is amended by adding the following new 
airworthiness directive:

96-26-07 BOEING: Amendment 39-9871. Docket 96-NM-266-AD.

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

    Note 1: This AD applies to each airplane identified in the 
preceding applicability provision, regardless of whether it has been 
modified, altered, or repaired in the area subject to the 
requirements of this AD. For airplanes that have been modified, 
altered, or repaired so that the performance of the requirements of 
this AD is affected, the owner/operator must request approval for an 
alternative method of compliance in accordance with paragraph (b) of 
this AD. The request should include an assessment of the effect of 
the modification, alteration, or repair on the unsafe condition 
addressed by this AD; and, if the unsafe condition has not been 
eliminated, the request should include specific proposed actions to 
address it.

    Compliance: Required as indicated, unless accomplished 
previously.
    To ensure that the flight crew is advised of the potential 
hazard associated with jammed or restricted flight controls and of 
the procedures necessary to address it, accomplish the following:
    (a) Within 30 days after the effective date of this AD, 
accomplish paragraphs (a)(1) and (a)(2) of this AD.
    (1) Revise the Emergency Procedures Section of the FAA-approved 
Airplane Flight Manual (AFM) to include the following recall item, 
which will enable the flight crew to take appropriate action to 
maintain control of the airplane during an uncommanded yaw or roll 
condition. This may be accomplished by inserting a copy of this AD in 
the AFM.

``UNCOMMANDED YAW OR ROLL

RECALL

    Maintain control of the airplane with all available flight 
controls. If roll is uncontrollable, immediately reduce angle of 
attack and increase airspeed. Do not attempt to maintain altitude 
until control is recovered. If engaged, disconnect autopilot and 
autothrottle.''
    (2) Revise the section entitled ``JAMMED FLIGHT CONTROLS'' of 
the Normal Procedures Section (for Model 737-100 and -200 series 
airplanes) or the Non-Normal Procedures Section (for Model 737-300, 
-400, and -500 series airplanes), as applicable, of the FAA-approved 
AFM to include the following procedures, which will enable the 
flight crew to take appropriate action to maintain control of the 
airplane and to correct a jammed or restricted flight control 
condition. This may be accomplished by inserting a copy of this AD 
in the AFM.

``JAMMED FLIGHT CONTROLS

JAMMED OR RESTRICTED ELEVATOR OR AILERON:

    In the event of a jammed elevator or aileron, do not hesitate to 
apply additional force to maintain control of the airplane. Do not 
turn off any flight control switches unless the faulty control is 
positively identified. Manual trim may be used to offload control 
forces.

JAMMED OR RESTRICTED RUDDER:

    If the rudder pedals will not move to the pilot commanded 
position, or if the pedals are deflected in one direction and 
jammed, maintain control of the airplane with all available flight 
controls. Disengage the autopilot and autothrottle. Use maximum 
force (combined effort by both pilots) to overpower the rudder 
system.
    After establishing control of the aircraft, check rudder pedal 
position. If the rudder pedals have centered, accomplish a normal 
descent, approach, and landing. If the rudder pedals remain jammed 
and are deflected to a degree that significantly affects the 
controllability of the airplane, select System B flight control 
switch to STBY RUD. If this action clears the jam/deflection, make a 
normal approach and landing, noting that rudder control may be 
limited. If moving the System B flight control switch to STBY RUD 
does not clear the jam, select System A flight control switch to 
off. If pedals do not center, select System B flight control switch 
to off. Make approach and landing with flaps 15 at VREF flaps 
15. The crosswind capability of the airplane will be greatly 
reduced.

YAW DAMPER:

    The yaw damper is a separate control and provides a limited 
rudder movement in opposition to the yaw rate of the airplane. 
Rudder (yaw damper) indicator displacement indicates yaw damper 
operation. Yaw damper light illuminates amber when the yaw damper is 
not engaged.
    (b) 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 Aircraft Certification 
Office (ACO), FAA, Transport Airplane Directorate. Operators shall 
submit their requests through an appropriate FAA Principal 
Operations Inspector, who may add comments and then send it to the 
Manager, Seattle ACO.

    Note 2: Information concerning the existence of approved 
alternative methods of compliance with this AD, if any, may be 
obtained from the Seattle ACO.

    (c) Special flight permits may be issued in accordance with 
sections 21.197 and 21.199 of the Federal Aviation Regulations (14 
CFR 21.197 and 21.199) to operate the airplane to a location where 
the requirements of this AD can be accomplished.
    (d) This amendment becomes effective on January 17, 1997.

    Issued in Renton, Washington, on December 23, 1996.
S.R. Miller,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 96-33104 Filed 12-30-96; 10:25 am]
BILLING CODE 4910-13-U