[Federal Register Volume 59, Number 79 (Monday, April 25, 1994)]
[Unknown Section]
[Page 0]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 94-9871]
[[Page Unknown]]
[Federal Register: April 25, 1994]
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DEPARTMENT OF TRANSPORTATION
14 CFR Part 39
[Docket No. 94-NM-17-AD]
Airworthiness Directives; Lockheed Model L-1011-385 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 Lockheed Model L-1011-385
series airplanes. This proposal would require an initial servicing or
overhaul of the ram air turbine (RAT), and incorporating repetitive
overhaul actions into the FAA-approved maintenance program. This
proposal is prompted by reports that, during routine maintenance of the
RAT, the turbine blade assembly separated during spin tests. The
actions specified by the proposed AD are intended to prevent separation
of the turbine blade assembly, which could damage the airplane
structure and systems, and, under certain circumstances, could lead to
reduced controllability of the airplane.
DATES: Comments must be received by June 20, 1994.
ADDRESSES: Submit comments in triplicate to the Federal Aviation
Administration (FAA), Transport Airplane Directorate, ANM-103,
Attention: Rules Docket No. 94-NM-17-AD, 1601 Lind Avenue SW., Renton,
Washington 98055-4056. Comments may be inspected at this location
between 9 a.m. and 3 p.m., Monday through Friday, except Federal
holidays.
The service information referenced in the proposed rule may be
obtained from Lockheed Western Export Company (LWEC), Field Support
Department, Dept. 693, Zone 0755, 2251 Lake Park Drive, Smyrna, Georgia
30080. This information may be examined at the FAA, Transport Airplane
Directorate, 1601 Lind Avenue, SW., Renton, Washington; or at the FAA,
Small Airplane Directorate, Atlanta Aircraft Certification Office,
suite 210C, 1669 Phoenix Parkway, Atlanta, Georgia.
FOR FURTHER INFORMATION CONTACT: Thomas Peters, Aerospace Engineer,
Flight Test Branch, ACE-160A, FAA, Small Airplane Directorate, Atlanta
Aircraft Certification Office, suite 210C, 1669 Phoenix Parkway,
Atlanta, Georgia 30349; telephone (404) 991-3915; fax (404) 991-3606.
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 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 94-NM-17-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. 94-NM-17-AD, 1601 Lind Avenue, SW., Renton, Washington
98055-4056.
Discussion
Recently, operators of certain Lockheed Model L-1011-385 series
airplanes have reported that, during routine maintenance of the ram air
turbine (RAT), the turbine blade assembly separated during functional
(spin) tests. Normal maintenance procedures call for operators
periodically to check the RAT functionally by using airplane hydraulic
pressure, pumped through the RAT, to spin the turbine. In the recently
reported incidents, the turbine blade separations occurred from 1.5 to
2 minutes into the functional test. Investigation into the cause of the
failures revealed that inadequately lubricated turbine bearings on the
RAT's led to the separation of the turbine blade assembly.
Historically, there have been no mandatory replacement or
refurbishment times for the RAT's installed on Model L-1011-385 series
airplanes. Under normal maintenance procedures, the RAT's are
functionally tested, on the an average, every 48 months or 4,000
flights (at a ``D'' check). The RAT is replaced, refurbished, or
repaired ``on condition'' only; that is, only if the RAT fails the
functional test. In the reported incidents, the RAT's had not been
serviced, nor had functional testing indicated that they needed
servicing, since new. It is likely that RAT's have been on many other
affected airplanes since delivery, with no servicing that would ensure
adequate lubrication of the turbine bearing.
Although all of the incidents of failure occurred while the
airplane was on the ground undergoing routine functional testing of the
RAT, the likelihood exists for these failures also to occur during
flight, if the RAT were deployed during an emergency. The RAT is used
during flight only in the event of failure of hydraulic power in all
four hydraulic systems of the airplane; this would most likely occur in
an ``all engines out'' situation. Separation of the turbine blade
assembly on the RAT could result in damage to the RAT, the airplane
structure, or systems, and could damage property or injure persons on
the ground. Failure of the RAT during an ``all engines out'' emergency
situation could result in complete loss of hydraulic power on the
airplane.
The FAA has reviewed and approved Lockheed TriStar L-1011 Service
Bulletin 093-29-098, dated December 6, 1993, that describes procedures
for removing, disassembling, inspecting, testing, and servicing of the
RAT. This service bulletin references Dowty Aerospace Hydraulics--
Cheltenham Service Bulletin RAT16C10-29-168, dated December 1, 1993, as
an additional source of service information for inspecting, testing,
and servicing the RAT's. (Dowty is the manufacturer of the subject
RAT's.) It also references Dowty Aerospace Hydraulics--Cheltenham
Service Bulletin RAT16C10-29-154, Revision 1, dated September 15, 1993,
which recommends overhauling the RAT every 8 years.
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 that operators initially either service the
RAT (which entails removal, disassembly, inspection, and testing) in
accordance with the Lockheed service bulletin described previously; or
completely overhaul the RAT in accordance with the RAT Overhaul Manual.
This proposal would also require revising the FAA-approved maintenance
program to incorporate procedures to overhaul the RAT at 8-year
intervals.
There are approximately 236 Lockheed Model L-1011-385 series
airplanes of the affected design in the worldwide fleet. The FAA
estimates that 117 airplanes of U.S. registry would be affected by this
proposed AD.
For operators electing initially to service the RAT, it would take
approximately 48 work hours per airplane to accomplish those actions,
at an average labor rate of $55 per work hour. Based on these figures,
the total cost impact of the proposed servicing actions on U.S.
operators is estimated to be $2,640 per RAT.
For operators electing initially to overhaul the RAT, it would take
approximately 170 work hours per RAT to accomplish those actions, at an
average labor rate of $55 per work hour. Based on these figures, the
total cost impact of the proposed overhaul actions on U.S. operators is
estimated to be $9,350 per RAT.
The number of work hours that would be required to perform either
the servicing or overhaul of the RAT, as indicated above, is presented
as if those actions were to be accomplished as ``stand alone'' actions.
However, in actual practice, these actions for the most part would be
accomplished coincidentally or in combination with normally scheduled
airplane inspections and other maintenance program tasks. Therefore,
the actual number of any necessary additional work hours would be
minimal in many instances. Additionally, any costs associated with
special airplane scheduling would be minimal.
Incorporation of the proposed requirements of this AD into the FAA-
approved maintenance program would require approximately 40 work hours
per operator to accomplish, at an average labor rate of $55 per work
hour. Based on these figures, the total cost impact of incorporation of
the proposed maintenance program change on U.S. operators is estimated
to be $2,200 per operator.
The FAA recognizes that the obligation to maintain aircraft in an
airworthy condition is vital, but sometimes expensive. Because AD's
require specific actions to address specific unsafe conditions, they
appear to impose costs that would not otherwise be borne by operators.
However, because of the general obligation of operators to maintain
aircraft in an airworthy condition, this appearance is deceptive.
Attributing those costs solely to the issuance of this AD is
unrealistic because, in the interest of maintaining safe aircraft, most
prudent operators would accomplish the required actions even if they
were not required to do so by the AD.
A full cost-benefit analysis has not been accomplished for this
proposed AD. As a matter of law, in order to be airworthy, an aircraft
must conform to its type design and be in a condition for safe
operation. The type design is approved only after the FAA makes a
determination that it complies with all applicable airworthiness
requirements. In adopting and maintaining those requirements, the FAA
has already made the determination that they establish a level of
safety that is cost-beneficial. When the FAA, as in this proposed AD,
makes a finding of an unsafe condition, this means that this cost-
beneficial level of safety is no longer being achieved and that the
proposed actions are necessary to restore that level of safety. Because
this level of safety has already been determined to be cost-beneficial,
a full cost-benefit analysis for this proposed AD would be redundant
and unnecessary.
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 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:
Lockheed: Docket 94-NM-17-AD.
Applicability: Model L-1011-385 series airplanes having serial
numbers 193A through 193Y inclusive, 293A through 293F inclusive,
and -1002 through -1250 inclusive; certificated in any category.
Compliance: Required as indicated, unless accomplished
previously.
To prevent separation of the turbine blade assembly, which could
damage the airplane structure and systems, and, under certain
circumstances, lead to reduced controllability of the airplane,
accomplish the following:
(a) Remove, disassemble, inspect, test, and service the ram air
turbine (RAT) in accordance with Lockheed TriStar L-1011 Service
Bulletin 093-29-098, dated December 6, 1993; or completely overhaul
the RAT in accordance with Chapter 29-21-01 of Dowty Aerospace
Hydraulics--Cheltenham Overhaul Manual; at the applicable time
specified in either paragraph (a)(1) or (a)(2) of this AD:
(1) For airplanes on which the RAT has not been serviced or
overhauled within 6 years prior to the effective date of this AD:
Accomplish the procedures within 2 years after the effective date of
this AD.
(2) For airplanes on which the RAT has been serviced or
overhauled within 6 years prior to the effective date of this AD in
accordance with a method that is equivalent to the procedures
described in Dowty Aerospace Hydraulics--Cheltenham Service Bulletin
RAT16C10-29-168, dated December 1, 1993: Accomplish the procedures
within 8 years after the date of the immediately preceding servicing
of the RAT.
(b) Within 24 months after the effective date of this AD, revise
the FAA-approved maintenance program to incorporate procedures for
complete overhaul of the RAT at intervals not to exceed 8 years, in
accordance with Chapter 29-21-01 of Dowty Aerospace Hydraulics--
Cheltenham Overhaul Manual.
(c) 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, Atlanta Aircraft Certification
Office (ACO), FAA, Small 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, Atlanta ACO.
Note: Information concerning the existence of approved
alternative methods of compliance with this AD, if any, may be
obtained from the Atlanta ACO.
(d) 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.
Issued in Renton, Washington, on April 19, 1994.
Darrell M. Pederson,
Acting Manager, Transport Airplane Directorate, Aircraft Certification
Service.
[FR Doc. 94-9871 Filed 4-22-94; 8:45 am]
BILLING CODE 4910-13-U
