Airworthiness Directives; McDonnell Douglas Model MD-11 and MD- 11F Series Airplanes Equipped With Honeywell Flight Management Computers

DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 94-NM-57-AD; Amendment 39-8910; AD 94-10-03]

Airworthiness Directives; McDonnell Douglas Model MD-11 and MD-

11F Series Airplanes Equipped With Honeywell Flight Management

Computers

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 certain McDonnell Douglas Model MD-11 and MD-11F

series airplanes. This action requires deactivation of the Visual

Omnidirectional Receiver/Localizer (VOR/LOC) option by revising the

program pin wiring for the Flight Management Computer/Flight Control

Computer (FMC/FCC). This amendment is prompted by reports of

uncommanded roll mode changes on these airplanes during takeoff and

landing due to incorrect initialization of VOR/LOC logic within the

FMC. The actions specified in this AD are intended to prevent the

airplane from deviating from its intended flight path due to an

uncommanded change in the course of direction.

DATES: Effective on May 23, 1994.

The incorporation by reference of certain publications listed in

the regulations is approved by the Director of the Federal Register as

of May 23, 1994.

Comments for inclusion in the Rules Docket must be received on or

before July 5, 1994.

ADDRESSES: Submit comments in triplicate to the Federal Aviation

Administration (FAA), Transport Airplane Directorate, ANM-103,

Attention: Rules Docket No. 94-NM-57-AD, 1601 Lind Avenue, SW., Renton,

Washington 98055-4056.

The service information referenced in this AD may be obtained from

McDonnell Douglas Corporation, P.O. Box 1771, Long Beach, California

90801-1771, Attention: business Unit Manager, Technical Administrative

support, Dept. L51, M.C. 2-98. This information may be examined at the

FAA, Transport Airplane Directorate, 1601 Lind Avenue, SW., Renton,

Washington; or at the FAA, Los Angeles Aircraft Certification Office,

Transport Airplane Directorate, 3229 East Spring Street, Long Beach,

California; or at the Office of the Federal Register, 800 North Capitol

Street, NW., suite 700, Washington, DC.

FOR FURTHER INFORMATION CONTACT: Natalie Phan-Tran, Aerospace Engineer,

Systems & Equipment Branch, ANM-130L, Los Angeles Aircraft

Certification Office, FAA, Transport Airplane Directorate, 3229 East

Spring Street, Long Beach, California 90806-2425; telephone (310) 988-

5343; fax (310) 988-5210.

SUPPLEMENTARY INFORMATION: The FAA has received reports of uncommanded

roll mode changes that have occurred on McDonnell Douglas Model MD-11

series airplanes during takeoff and landing. The airplanes involved in

these incidents have been equipped with Honeywell Flight Management

Computers (FMC) having part numbers 4059050-907 and 4059050-908. The

incidents occurred when these FMC's were operating with the Visual

Omnidirectional Receiver/Localizer (VOR/LOC) option selected.

Investigation revealed that these incidents of uncommanded roll

mode changes were caused by one of the two FMC's not automatically

resetting or clearing all VOR mode logic upon landing. If the VOR mode

was selected on the previous inbound flight, and if this VOR mode is

not automatically cleared after the airplane lands, the VOR logic may

remain valid (in operation) in one of the two FMC's onboard the

airplane. If, during a subsequent flight, the autoflight system is

engaged to the FMC that still has the valid VOR logic [either by

disconnecting the autopilot (AP) or by swapping autopilots (AP1 to AP2,

or vice versa) with the ``AUTOFLIGHT'' switch], that FMC will

automatically command the airplane into a VOR roll mode. The airplane

will then follow this VOR mode logic guidance and fly in a direction

not planned by the flight crew. Such an uncommanded change in course

direction, if not corrected, could result in the airplane deviating

from its intended flight path.

The FAA has reviewed and approved McDonnell Douglas MD-11 Alert

Service Bulletin A34-55, dated April 22, 1994, that describes

procedures for deactivating the VOR/LOC option on the subject Honeywell

FMC's by removing the VOR/LOC pin from the Flight Management Computer/

Flight Control Computer (FMC/FCC) configuration plug on the main

avionics rack. This procedure will minimize the possibility of

uncommanded roll mode changes.

Since an unsafe condition has been identified that is likely to

exist or develop on other Model MD-11 and MD-11F series airplanes of

the same type design, this AD is being issued to prevent the airplane

from deviating from its intended flight path due to an uncommanded

change in the course of direction. This AD requires deactivating the

VOR/LOC option on certain Honeywell FMC's by removing the VOR/LOC pin

from the FMC/FCC configuration plug on the main avionics rack. The

actions are required to be accomplished in accordance with the service

bulletin described previously.

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 notice must submit a self-addressed,

stamped postcard on which the following statement is made: ``Comments

to Docket Number 94-NM-57-AD.'' The postcard will be date stamped and

returned to the commenter.

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 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 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, Incorporation by

reference, Safety.

Adoption of the Amendment

Accordingly, pursuant to the authority delegated to me by the

Administrator, the Federal Aviation Administration amends 14 CFR part

39 of the Federal Aviation Regulations as follows:

PART 39--AIRWORTHINESS DIRECTIVES

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

Authority: 49 U.S.C. App. 1354(a), 1421 and 1423; 49 U.S.C.

106(g); and 14 CFR 11.89.

Sec. 39.13 [Amended]

2. Section 39.13 is amended by adding the following new

airworthiness directive:

94-10-03 McDonnell Douglas: Amendment 39-8910. Docket 94-NM-57-AD.

Applicability: Model MD-11 and MD-11F series airplanes; equipped

with Honeywell Flight Management Computers having part numbers

4059050-907 or 4059050-908; certificated in any category.

Compliance: Required as indicated, unless accomplished

previously.

To prevent the airplane from deviating from its intended flight

path due to an uncommanded change in the course of direction,

accomplish the following:

(a) Within 30 days after the effective date of this AD,

deactivate the Visual Omnidirectional Receiver/Localizer (VOR/LOC)

option by removing the VOR/LOC pin from the Flight Management

Computer/Flight Control Computer (FMC/FCC) configuration plug on the

main avionics rack, in accordance with McDonnell Douglas MD-11 Alert

Service Bulletin A34-55, dated April 22, 1994.

(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, Los Angeles Aircraft Certification

Office (ACO). Operators shall submit their requests through an

appropriate FAA Principal Avionics Inspector, who may add comments

and then send it to the Manager, Los Angeles ACO.

Note: Information concerning the existence of approved

alternative methods of compliance with this AD, if any, may be

obtained from the Los Angeles 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) The deactivation procedure shall be done in accordance with

McDonnell Douglas MD-11 Alert Service Bulletin A34-55, dated April

22, 1994. This incorporation by reference was approved by the

Director of the Federal Register in accordance with 5 U.S.C. 552(a)

and 1 CFR Part 51. Copies may be obtained from McDonnell Douglas

Corporation, P.O. Box 1771, Long Beach, California 90801-1771,

Attention: business Unit Manager, Technical Administrative support,

Dept. L51, M.C. 2-98. Copies may be inspected at the FAA, Transport

Airplane Directorate, 1601 Lind Avenue, SW., Renton, Washington; or

at the FAA, Los Angeles Aircraft Certification Office, Transport

Airplane Directorate, 3229 East Spring Street, Long Beach,

California; or at the Office of the Federal Register, 800 North

Capitol Street, NW., suite 700, Washington, DC.

(e) This amendment becomes effective on May 23, 1994.

Issued in Renton, Washington, on April 29, 1994.

James V. Devany,

Acting Manager, Transport Airplane Directorate, Aircraft Certification

Service.

[FR Doc. 94-10776 Filed 5-5-94; 8:45 am]

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