Airworthiness Directives; Lockheed Model L-1011-385 Series Airplanes

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]

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