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-29-AD; Amendment 39-8879; AD 94-08-07]

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 revising the FAA-approved

Airplane Flight Manual (AFM) to ensure that the flight crews verify the

accuracy of data provided by the Flight Management Computer (FMC) under

certain conditions. This amendment is prompted by a report that certain

FMC's may provide erroneous V speed data under certain conditions. The

actions specified in this AD are intended to prevent the airplane from

failing to achieve sufficient climb gradient, which may result in the

airplane failing to achieve obstacle clearance.

DATES: Effective April 28, 1994.

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

before June 13, 1994.

ADDRESSES: Submit comments in triplicate to the Federal Aviation

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

Attention: Rules Docket No. 94-NM-29-AD, 1601 Lind Avenue, SW., Renton,

Washington 98055-4056.

Information concerning this amendment may be obtained from or

examined at the FAA, Transport Airplane Directorate, 1601 Lind Avenue,

SW., Renton, Washington; or at the FAA, Transport Airplane Directorate,

Los Angeles Aircraft Certification Office, 3229 East Spring Street,

Long Beach, California.

FOR FURTHER INFORMATION CONTACT: Thomas A. Enyart, Aerospace Engineer,

Flight Test Branch, ANM-162L, FAA, Transport Airplane Directorate, Los

Angeles Aircraft Certification Office, 3229 East Spring Street, Long

Beach, California 90806-2425; telephone (310) 988-5372; fax (310) 988-

5210.

SUPPLEMENTARY INFORMATION: Recently, an operator of McDonnell Douglas

Model MD-11 series airplanes reported that certain Honeywell Flight

Management Computers (FMC) provided erroneous V speed data when the

anti-ice system was turned ON during flex (assumed) temperature

takeoffs. Investigation into this problem revealed that the takeoff

decision speed (V1) could be as low as 12 knots below the V1

speed data published in the FAA-approved Airplane Flight Manual (AFM),

and the rotation speed (VR) could be as low as 4 knots below the

VR speed data published in the FAA-approved AFM. An airplane

rotating at low VR speeds could reach 35 feet at a speed less than

the published minimum safety speed (V2). This condition, if not

corrected, could result in these airplanes failing to achieve

sufficient climb gradient, which may lead to these airplanes failing to

achieve obstacle clearance.

The FMC's installed on Model MD-11 series airplanes are identical

to those installed Model MD-11F series airplanes.

Since an unsafe condition has been identified that is likely to

exist or develop on other McDonnell Douglas Model MD-11 and MD-11F

series airplanes of the same type design equipped with certain

Honeywell FMC's, this AD is being issued to prevent these airplanes

from failing to achieve sufficient climb gradient, which may result in

these airplanes failing to achieve obstacle clearance. This AD requires

revising the FAA-approved AFM to ensure that the flight crews verify

the accuracy of data provided by the FMC when the anti-ice system is

turned ON during flex temperature takeoffs.

This is considered to be interim action. The manufacturer of these

airplanes is currently developing new software, in concert with the

manufacturer of the FMC, that will address the unsafe condition

addressed by this AD. Once this software is developed, approved, and

available, the FAA may consider additional rulemaking.

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-29-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, 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:

94-08-07 McDonnell Douglas: Amendment 39-8879. Docket 94-NM-29-AD.

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

with Honeywell Flight Management Computers having part numbers

4059050-906, -907, and -908; certificated in any category.

Compliance: Required as indicated, unless accomplished

previously.

To prevent the airplane from failing to achieve sufficient climb

gradient, which may result in the airplane failing to achieve

obstacle clearance, accomplish the following:

(a) Within 20 days after the effective date of this AD, revise

the Limitations Section (Section 1) of the FAA-approved Airplane

Flight Manual (AFM), page 5-1, FLIGHT GUIDANCE, Flight Management

System (FMS) Section, to include the following information. This may

be accomplished by inserting a copy of this AD or an FAA-approved

McDonnell Douglas AFM revision in the AFM.

For any approved thrust level, the FMS computed V1,

VR, and V2 must be verified with AFM derived data, unless

all of the following conditions are met:

Dry Runway.

Balanced Field Length.

Ice Protection OFF.

(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), 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, 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

Federal Aviation Regulations (FAR) 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 April 28, 1994.

Issued in Renton, Washington, on April 6, 1994.

Darrell M. Pederson,

Acting Manager, Transport Airplane Directorate, Aircraft Certification

Service.

[FR Doc. 94-8686 Filed 4-12-94; 8:45 am]

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