[Federal Register Volume 61, Number 77 (Friday, April 19, 1996)]
[Proposed Rules]
[Pages 17259-17261]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 96-9691]
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DEPARTMENT OF TRANSPORTATION
14 CFR Part 39
[Docket No. 95-NM-211-AD]
Airworthiness Directives; McDonnell Douglas Model MD-11 Series
Airplanes
AGENCY: Federal Aviation Administration, DOT.
ACTION: Notice of proposed rulemaking (NPRM).
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SUMMARY: This document proposes the adoption of a new airworthiness
directive (AD) that is applicable to certain McDonnell Douglas Model
MD-11 series airplanes. This proposal would require either replacement
or modification of the inboard and outboard flap actuators. This
proposal is prompted by a report of failure of the piston rod of the
inboard flap actuator due a manufacturing process error. The actions
specified by the proposed AD are intended to prevent failure of the
piston rod, which could result in uncommanded flap extension and could
lead to an asymmetric flap configuration, which could reduce
controllability of the airplane.
DATES: Comments must be received by May 31, 1996.
ADDRESSES: Submit comments in triplicate to the Federal Aviation
Administration (FAA), Transport Airplane Directorate, ANM-103,
Attention: Rules Docket No. 95-NM-211-AD, 1601 Lind Avenue SW., Renton,
Washington 98055-4056. Comments may be inspected at this location
between 9:00 a.m. and 3:00 p.m., Monday through Friday, except Federal
holidays. -
The service information referenced in the proposed rule may be
obtained from McDonnell Douglas Corporation, 3855 Lakewood Boulevard,
Long Beach, California 90846, Attention: Technical Publications
Business Administration, Department C1-L51 (2-60). This information may
be examined at the FAA, Transport Airplane Directorate, 1601 Lind
Avenue SW., Renton, Washington.
FOR FURTHER INFORMATION CONTACT: Andrew Gfrerer, Aerospace Engineer,
Systems and Equipment Branch, ANM-130L, FAA, Los Angeles Aircraft
Certification Office, 3960 Paramount Boulevard, Lakewood, California
90712; telephone (310) 627-5338; fax (310) 627-5210.
SUPPLEMENTARY INFORMATION:
Comments Invited
Interested persons are invited to participate in the making of the
proposed 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 above. All
communications received on or before the closing date for comments,
specified above, will be considered before taking action on the
proposed rule. The proposals contained in this notice may be changed in
light of the comments received.
Comments are specifically invited on the overall regulatory,
economic, environmental, and energy aspects of the proposed 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 summarizing each FAA-public contact
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concerned with the substance of this proposal 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 95-NM-211-AD.'' The postcard will be date stamped and
returned to the commenter.
Availability of NPRMs
Any person may obtain a copy of this NPRM by submitting a request
to the FAA, Transport Airplane Directorate, ANM-103, Attention: Rules
Docket No. 95-NM-211-AD, 1601 Lind Avenue SW., Renton, Washington
98055-4056.
Discussion
The FAA has received a report of failure of the piston rod of the
inboard flap actuator on a Model MD-11 series airplane. This failure
occurred on the ground as the pilot was commanding the flaps to
retract. Analysis of the incident determined that hydraulic fluid
flowed through the broken piston rod and forced the flap to extend. The
extending inboard piston rod and flap had enough power to drive the two
outboard flaps to the extend position by way of the linking cables used
to keep the flaps symmetrical. Initial investigation revealed that the
apparent cause of this failure was an isolated case of a manufacturing
process error. However, further review revealed that the existing
design of the subject area is such that a broken piston rod is a
single-point failure of the flight control system that can drive a flap
to the extend position during any phase of flight. Such an uncommanded
flap extension, if not corrected, could cause an asymmetric flap
condition in the airplane and possibly could result in an uncommanded
roll. In addition, if this situation were to occur at altitude on an
extended overwater flight, the flap extension would cause increased
drag and decrease the airplane's range so that it may be unable to
reach its final destination.
The FAA has reviewed and approved McDonnell Douglas Alert Service
Bulletin MD11-27A057, dated August 31, 1995, which describes procedures
for:
Option 1: replacement of the inboard and outboard flap
actuators with new actuators; or
Option 2: modification and reidentification of the inboard
and outboard flap actuators; or
Option 3: modification and reidentification of the inboard
flap inboard actuator, the inboard flap outboard actuator, and the
outboard flap actuators.
The modification of the actuators involves drilling a hole in the
rod assembly and installing a rivet blow-out plug.
Accomplishment of any one of these options will minimize the
possibility of uncommanded flap extension in the event of a piston rod
failure.
Since an unsafe condition has been identified that is likely to
exist or develop on other products of this same type design, the
proposed AD would require either the replacement or modification of the
flap actuators in accordance with either Option 1, Option 2, or Option
3, as described in the alert service bulletin discussed previously.
There are approximately 143 McDonnell Douglas Model MD-11 series
airplanes of the affected design in the worldwide fleet. The FAA
estimates that 52 airplanes of U.S. registry would be affected by this
proposed AD.
To accomplish the proposed actions associated with Option 1
(replacement of flap actuators) would take approximately 9 work hours
per airplane, at an average labor rate of $60 per work hour. Required
parts would be supplied by the manufacturer at no cost to the
operators. Based on these figures, the cost impact of Option 1 proposed
by this AD on U.S. operators is estimated to be $540 per airplane.
To accomplish the proposed action associated with Option 2
(modification and reidentification of the inboard and outboard flap
actuators) would take approximately 25 work hours per airplane, at an
average labor rate of $60 per work hour. Required parts would be
supplied by the manufacturer at no cost to the operators. Based on
these figures, the cost impact of Option 2 proposed by this AD on U.S.
operators is estimated to be $1,500 per airplane.
To accomplish the proposed actions associated with Option 3
(modification and reidentification of the inboard flap inboard
actuator, the inboard flap outboard actuator, and the outboard flap
actuators) would take approximately 27 work hours per airplane, at an
average labor rate of $60 per work hour. Required parts would be
supplied by the manufacturer at no cost to the operators. Based on
these figures, the cost impact of Option 3 proposed by this AD on U.S.
operators is estimated to be $1,620 per airplane.
Based on the figures discussed above, the cost impact of this
proposed AD action on U.S. operators is estimated to be between $28,080
and $82,240 for the affected fleet. These cost impact figures are based
on assumptions that no operator has yet accomplished any of the
proposed requirements of this AD action, and that no operator would
accomplish those actions in the future if this AD were not adopted.
The regulations proposed herein would 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
proposal would not have sufficient federalism implications to warrant
the preparation of a Federalism Assessment.
For the reasons discussed above, I certify that this proposed
regulation (1) is not a ``significant regulatory action'' under
Executive Order 12866; (2) is not a ``significant rule'' under the DOT
Regulatory Policies and Procedures (44 FR 11034, February 26, 1979);
and (3) if promulgated, will not have a significant economic impact,
positive or negative, on a substantial number of small entities under
the criteria of the Regulatory Flexibility Act. A copy of the draft
regulatory evaluation prepared for this action is contained in the
Rules Docket. A copy of it may be obtained by contacting 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.
The Proposed Amendment
Accordingly, pursuant to the authority delegated to me by the
Administrator, the Federal Aviation Administration proposes to amend
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:
McDonnell Douglas: Docket 95-NM-211-AD.
Applicability: Model MD-11 series airplanes, manufacturer's
fuselage numbers 0447 through 0589 inclusive, 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
[[Page 17261]]
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 prevent failure of the piston rod, which could result in
uncommanded flap extension and resultant asymmetric flap
configuration, which could reduce controllability of the airplane,
accomplish the following:
(a) Within 6 months after the effective date of this AD,
accomplish either paragraph (a)(1), (a)(2), or (a)(3) of this AD, in
accordance with McDonnell Douglas Alert Service Bulletin MD11-
27A057, dated August 31, 1995.
(1) Accomplish the actions specified as Option 1 (replacement of
the inboard and outboard flap actuators) in the Accomplishment
Instructions of the alert service bulletin; or
(2) Accomplish the actions specified as Option 2 (modification
and reidentification of the inboard and outboard flap actuators) in
the Accomplishment Instructions of the alert service bulletin; or
(3) Accomplish the actions specified as Option 3 (modification
and reidentification of the inboard flap inboard actuator, inboard
flap outboard actuator, and outboard flap actuators) in the
Accomplishment Instructions of the alert service bulletin
(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
Maintenance Inspector, who may add comments and then send it to the
Manager, Los Angeles ACO.
Note 2: 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.
Issued in Renton, Washington, on April 15, 1996.
Darrell M. Pederson,
Acting Manager, Transport Airplane Directorate, Aircraft Certification
Service.
[FR Doc. 96-9691 Filed 4-18-96; 8:45 am]
BILLING CODE 4910-13-U
