[Federal Register Volume 59, Number 194 (Friday, October 7, 1994)]
[Unknown Section]
[Page 0]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 94-24872]
[[Page Unknown]]
[Federal Register: October 7, 1994]
=======================================================================
-----------------------------------------------------------------------
DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 39
[Docket No. 94-NM-160-AD; Amendment 39-9042; AD 94-19-51 R1]
Airworthiness Directives; McDonnell Douglas Model MD-11 and MD-
11F Series Airplanes
AGENCY: Federal Aviation Administration, DOT.
ACTION: Final rule; request for comments.
-----------------------------------------------------------------------
SUMMARY: This document revises and publishes in the Federal Register an
amendment adopting Airworthiness Directive (AD) T94-19-51 that was sent
previously to all known U.S. owners and operators of McDonnell Douglas
Model MD-11 and MD-11F series airplanes by individual telegrams. This
AD supersedes an existing airworthiness directive that currently
requires a revision to the 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
requires a revision to the AFM to ensure that the flight crews verify
the accuracy of data provided by the FMC under all conditions. This
amendment is prompted by a report that the ``check/confirm V speed''
message may be inhibited when the flaps are extended to within three
degrees of the takeoff flap setting that was entered into the FMC. The
actions specified by this AD are intended to prevent FMC
miscalculations that may result in excessively high takeoff decision
(V1) speeds, which may adversely affect accelerate-stop distances
and may lead to the failure of the airplane to stop prior to departing
the end of the runway during a high speed rejected takeoff. This
amendment also revises the previously issued telegraphic AD by
correcting a typographical error in the listing of the part numbers for
the FMC's.
DATES: Effective October 24, 1994, to all persons except those persons
to whom it was made immediately effective by telegraphic AD T94-19-51,
issued on September 14, 1994, which contained the requirements of this
amendment.
Comments for inclusion in the Rules Docket must be received on or
before December 6, 1994.
ADDRESSES: Information concerning this amendment may be obtained from
or examined at the Federal Aviation Administration (FAA), Transport
Airplane Directorate, Rules Docket, 1601 Lind Avenue, SW., Renton,
Washington 98055-4056.
Submit comments in triplicate to the Federal Aviation
Administration (FAA), Transport Airplane Directorate, ANM-103,
Attention: Rules Docket No. 94-NM-160-AD, 1601 Lind Avenue, SW.,
Renton, Washington 98055-4056.
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: On April 6, 1994, the FAA issued AD 94-08-
07, amendment 39-8879 (59 FR 17467, April 13, 1994), to require
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) when the anti-ice system is turned on during
flex (assumed) temperature takeoffs. That AD does not require that
these procedures be followed if the runway is dry, if the field length
is balanced, or if the ice protection is turned off. That action was
prompted by a report that certain Honeywell FMC's provided erroneous V
speed data when the anti-ice system was turned on during flex
temperature takeoffs. The FAA determined that this phenomenon may occur
on McDonnell Douglas Model MD-11 and MD-11F series airplanes equipped
with Honeywell FMC's having part numbers 4059050-906, -907, and -908.
That condition, if not corrected, could result in the airplane failing
to achieve sufficient climb gradient, which may result in the airplane
failing to achieve obstacle clearance.
Since the issuance of that AD, the FAA has received a report that
the ``check/confirm V speed'' message may be inhibited when the flaps
are extended to within three degrees of the takeoff flap setting that
was entered into the FMC. Under normal operating conditions, the FMC
calculates V speeds based on data the pilot enters into the FMC and
data the FMC receives from the aircraft sensors, including total air
temperature (TAT). Investigation revealed that on hot sunny days, the
TAT probe may indicate an erroneously high ambient temperature that is
up to 15 degrees Celsius higher than the actual ambient temperature.
The FMC, however, was supposedly designed and certified to account for
this error in the actual ambient temperature by continually
recalculating the V speed data and indicating a ``check/confirm V
speed'' message when the calculations indicate that the V speeds differ
by more than two knots from the V speeds entered into the FMC by the
pilot. However, if the flaps are set to the takeoff position prior to
the TAT probe temperature reaching the ambient temperature, that
message would be inhibited and the pilot would not be notified that the
indicated V speed is incorrect. The FAA has determined that such
erroneous indications may result in an FMC calculation of the takeoff
decision speed (V1) that is up to six knots greater than the
actual V1 speed.
FMC miscalculations that result in excessively high V1 speeds
could result in accelerate-stop distances that exceed planned takeoff
distances, which may lead to the airplane departing the end of the
runway during a high speed rejected takeoff.
Since the unsafe condition described is likely to exist or develop
on other McDonnell Douglas Model MD-11 and MD-11F series airplanes of
the same type design, the FAA issued telegraphic AD T94-19-51, on
September 14, 1994, to supersede AD 94-08-07 and to require a revision
to the FAA-approved AFM to ensure that the flight crews verify the
accuracy of data provided by the FMC under all conditions. The AD also
requires that V speeds be manually entered into the FMC.
This is considered to be interim action. The manufacturer of these
airplanes, in concert with the manufacturer of the FMC, is currently
developing new software that will address the unsafe condition
addressed by this AD. Once this software is developed, approved, and
available, the FAA may consider additional rulemaking.
Additionally, subsequent to the issuance of telegraphic AD T94-19-
51, the FAA discovered that a typographical error appeared in the
listing of affected part numbers for the Honeywell FMC's. The part
numbers were inadvertently listed as ``4059040-906, -907, and -908.''
The correct part numbers are ``4059050-906, -907, and -908.'' (These
correct part numbers were listed correctly in the preamble to the
telegraphic AD and in the previously-issued AD 94-08-07.)
Since it was found that immediate corrective action was required,
notice and opportunity for prior public comment thereon were
impracticable and contrary to the public interest, and good cause
existed to make the AD effective immediately by individual telegrams
issued on September 14, 1994, to all known U.S. owners and operators of
McDonnell Douglas Model MD-11 and MD-11F series airplanes. These
conditions still exist, and the AD is hereby published in the Federal
Register as an amendment to section 39.13 of the Federal Aviation
Regulations (14 CFR 39.13) to make it effective to all persons.
Additionally, this AD revises the telegraphic AD by correcting a
typographical error in the listing of FMC part numbers.
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 94-NM-160-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 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. 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 removing amendment 39-8879 (59 FR
17467, April 13, 1994), and by adding a new airworthiness directive
(AD), amendment 39-9042, to read as follows:
94-19-51 R1 McDonnell Douglas: Amendment 39-9042. Docket 94-NM-160-
AD. Supersedes AD 94-08-07, amendment 39-8879.
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 departing the end of the runway
during a high speed rejected takeoff, accomplish the following:
(a) Within 7 days after the effective date of this AD, replace
the revision to the Limitations Section (Section 1) of the FAA-
approved Airplane Flight Manual (AFM), page 5-1, FLIGHT GUIDANCE,
Flight Management System (FMS) Section, that was required by AD 94-
08-07, amendment 39-8879, with 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 speeds must be verified with AFM derived data
and manually entered.''
(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
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 October 24, 1994, to all
persons except those persons to whom it was made immediately
effective by telegraphic AD T94-19-51, issued on September 14, 1994,
which contained the requirements of this amendment.
Issued in Renton, Washington, on October 3, 1994.
S.R. Miller,
Acting Manager, Transport Airplane Directorate, Aircraft Certification
Service.
[FR Doc. 94-24872 Filed 10-6-94; 8:45 am]
BILLING CODE 4910-13-P
