Airworthiness Directives; Boeing Model 757 Series Airplanes Equipped With Pratt and Whitney PW2000 Series Engines

DEPARTMENT OF TRANSPORTATION

14 CFR Part 39

[Docket No. 92-NM-173-AD; Amendment 39-8792; AD 94-01-10]

Airworthiness Directives; Boeing Model 757 Series Airplanes

Equipped With Pratt and Whitney PW2000 Series Engines

AGENCY: Federal Aviation Administration, DOT.

ACTION: Final rule.

-----------------------------------------------------------------------

SUMMARY: This amendment supersedes an existing airworthiness directive

(AD), applicable to certain Boeing Model 757 series airplanes, that

currently requires inspections, adjustments, and functional checks of

the engine thrust reverser system; and modification of the engine

thrust reverser directional control valve. This amendment adds a

requirement for installation of an additional thrust reverser system

locking feature; revises the compliance time for accomplishing the

modification; adds airplanes to the applicability; and requires

periodic functional tests of the locking feature following its

installation. This amendment is prompted by results of a safety review

of the thrust reverser system on these airplanes. The actions specified

by this AD are intended to prevent deployment of a thrust reverser in

flight and subsequent reduced controllability of the airplane.

DATES: Effective March 3, 1994.

The incorporation by reference of Boeing Service Bulletin 757-78-

0028, Revision 1, dated October 29, 1992, and Boeing Service Bulletin

757-78-0028, Revision 2, dated January 14, 1993, as listed in the

regulations, is approved by the Director of the Federal Register as of

March 3, 1994.

The incorporation by reference of certain other publications listed

in the regulations was approved previously by the Director of the

Federal Register as of September 16, 1991 (56 FR 46725, September 16,

1991).

ADDRESSES: The service information referenced in this AD may be

obtained from Boeing Commercial Airplane Group, P.O. Box 3707, Seattle,

Washington 98124-2207. This information may be examined at the Federal

Aviation Administration (FAA), Transport Airplane Directorate, Rules

Docket, 1601 Lind Avenue SW., Renton, Washington; or at the Office of

the Federal Register, 800 North Capitol Street, NW., suite 700,

Washington, DC.

FOR FURTHER INFORMATION CONTACT: Jeffrey Duven, Aerospace Engineer,

Propulsion Branch, ANM-140S, FAA, Transport Airplane Directorate,

Seattle Aircraft Certification Office, 1601 Lind Avenue, SW., Renton,

Washington 98055-4056; telephone (206) 227-2688; fax (206) 227-1181.

SUPPLEMENTARY INFORMATION: A proposal to amend part 39 of the Federal

Aviation Regulations by superseding AD 91-20-09, Amendment 39-8043 (56

FR 46725, September 16, 1991), which is applicable to certain Boeing

Model 757 series airplanes equipped with Pratt and Whitney PW2000

series engines, was published as a supplemental notice of proposed

rulemaking (NPRM) in the Federal Register on August 6, 1993 (58 FR

42034). The action proposed to require certain inspections,

adjustments, and functional checks of the engine thrust reverser

system; modification of the engine thrust reverser directional control

valve; installation of an additional thrust reverser system locking

feature (sync lock); and periodic functional tests of the locking

feature following its installation.

Interested persons have been afforded an opportunity to participate

in the making of this amendment. Due consideration has been given to

the comments received.

One commenter supports the proposed rule.

One commenter requests that paragraph (e) of the proposed rule be

revised to require only the ``sync lock test'' portion of the proposed

functional test. The commenter indicates that the proposed ``Thrust

Reverser Auto Restow and Sync Lock Test'' is a combination test

procedure that consists of an auto restow test of the entire thrust

reverser assembly and a test of the sync lock mechanism. The commenter

believes that this combination test procedure is more extensive than

that which is necessary to verify proper functioning of the sync lock.

The FAA concurs with the commenter's request. The FAA's objective

in proposing periodic functional tests of the sync lock device is to

ensure the integrity of the locking function. The FAA included the auto

restow portion of the functional test in the proposal because the

airplane maintenance manual does not distinguish between the sync lock

test and the auto restow test. However, since issuance of the proposal,

Boeing has submitted to the FAA separate procedures for accomplishment

of the sync lock integrity test described in the airplane maintenance

manual. These procedures are accomplished independently of the auto

restow test and other thrust reverser system tests. Accordingly, the

FAA has revised paragraph (e) of the final rule to remove the

requirement to accomplish the auto restow portion of the functional

test and to specify instructions for accomplishment of the sync lock

integrity test only.

The Air Transport Association (ATA) of America, on behalf of

several of its members, requests that the FAA review its justification

for including in an AD the functional test requirements proposed in

paragraph (e). ATA members are not opposed to accomplishing the

proposed tests as part of their maintenance programs, but are opposed

to accomplishing the tests as part of the requirements of this AD. The

commenters believe that the adoption of paragraph (e), as proposed, is

equivalent to issuing a Certification Maintenance Requirements (CMR)

item by means of an AD.

The FAA does not concur. The FAA acknowledges that similarities

exist between the periodic functional tests of the sync lock, as

required by paragraph (e) of this AD, and tasks denoted as CMR items.

The extent of those similarities is that both CMR items and the

periodic functional tests required by this AD place specific

requirements on operators of Model 757 series airplanes with respect to

scheduling airplane maintenance activities.

Generally, CMR items define specific repetitive inspections or

component replacements for equipment, systems, and installations.

Accomplishment of these CMR items ensures that the likelihood of

certain failures that could occur during operation of the airplane does

not exceed the limitations specified in Federal Aviation Regulations

(FAR) 25.1309, which is applicable to the design and approval of

transport category airplanes.

These CMR items are identified as a result of safety analyses of

airplane electrical, electronic, pressurization, and propulsion

systems. These analyses must be completed and approved by the FAA prior

to its issuance of an airplane Type Certificate (TC). Following

issuance of the TC, other necessary inspections, component

replacements, or overhaul intervals for airplane systems that are based

on in-service experience with the airplane, but that do not result in

re-evaluation of the basic safety analysis on which approval of the

system is based, are not included as additional CMR items; rather,

these are addressed through changes to the airplane maintenance program

or as the subjects of AD's.

In conclusion, while the effect of a CMR item is the same as that

of an AD requirement, its derivation is different. A CMR item is based

on a statistical analysis required by FAR 25.1309; an AD requirement is

based on follow-up work that is necessary to address an unsafe

condition that is likely to exist or develop on other airplanes of the

same type design.

This AD addresses an unsafe condition identified as deployment of a

thrust reverser during flight, and requires the installation of an

additional thrust reverser system locking feature to correct that

unsafe condition. The periodic functional tests contained in paragraph

(e) of this AD are not the result of a re-evaluation of the safety

analyses for Model 757 series airplanes with respect to FAR 25.1309

requirements. These tests have been established to ensure the

effectiveness of the modification required to address the identified

unsafe condition. The FAA considers issuance of this AD to be

necessary, since AD's are the means by which accomplishment of

procedures and adherence to specific compliance times are made

mandatory.

ATA states further that, if the FAA finds sufficient justification

to include the functional test requirements in this AD, an alternative

to accomplishing paragraph (e) should be provided in the final rule.

That alternative would include the following:

1. Within 3 months after accomplishing the sync lock installation,

operators would be required to revise the FAA-approved maintenance

inspection program to include a functional test of the sync lock. The

initial test would be accomplished within 1,000 hours time-in-service

after modification. This AD would no longer be applicable for operators

that have acceptably revised the maintenance program.

2. Operators complying with this suggested alternative could use an

alternative recordkeeping method in place of that otherwise required by

FAR 91.417 or 121.380.

3. For operators complying with this suggested alternative, the FAA

would be defined as the cognizant Principal Maintenance Inspector

(PMI).

ATA reasons that its suggested alternative to accomplishing

paragraph (e) of this AD is justified because no data exist to show

that repetitive tests of a modified thrust reverser cannot be handled

adequately through an operator's maintenance program.

The FAA does not concur. As discussed previously, the FAA has

determined that repetitive functional tests are necessary to ensure

that the sync lock modification is effective in preventing the

identified unsafe condition. This determination is based on the fact

that the sync lock is a new design whose reliability has not been

adequately proven through service experience. The ATA's proposal would

enable each operator to determine whether and how often these tests

should be conducted. In light of the severity of the identified unsafe

condition, the FAA has determined that allowing this degree of operator

discretion is inappropriate at this time. However, as the FAA obtains

further information with regard to in-service experience, it may

consider revising the requirements of paragraph (e) of this AD based on

that new data.

One commenter, Boeing, opposes the requirement contained in

paragraph (e) of the proposal for periodic functional tests of the sync

lock following accomplishment of the sync lock installation, and

proposes that the paragraph be removed until the FAA reviews the ``more

comprehensive'' scheduled maintenance recommendations developed by the

Model 757/767 Thrust Reverser Working Group (TRWG). Boeing indicates

that these more comprehensive tests will be recommended for maintenance

of the thrust reverser system in the next revision to the Maintenance

Review Board (MRB) report. Boeing also adds that the proposed interval

at which the tests specified in paragraph (e) of this AD must be

accomplished will be inconsistent with the next revision to the MRB

report.

Boeing states that any scheduled maintenance requirements for

airplanes on which the sync lock installation has been accomplished

should be presented at a Model 757 Industry Steering Committee meeting

with the FAA, which is scheduled for December 1993. Boeing adds that,

contingent upon FAA approval, recommendations developed by the TRWG

will be included in Revision D to the MRB report, which will be

published in the first quarter of 1994. Boeing believes that adoption

of the maintenance recommendations contained in the forthcoming

revision to the MRB report will ensure that an adequate level of

safety, with regard to the sync lock installation, will be maintained

by all operators of Model 757 series airplanes.

The FAA does not concur with the commenter's request. The FAA finds

that addressing the sync lock integrity test in a recommended action,

such as the MRB report, will not ensure an acceptable level of safety

with regard to the thrust reverser maintenance program. The FAA has

determined that requiring the periodic functional tests of the sync

lock integrity in this AD will provide an adequate level of safety.

The FAA recognizes that differences exist currently where this AD

requires that the sync lock integrity test be accomplished at more

frequent intervals than those currently proposed by Boeing for

inclusion in the MRB report. However, the FAA has determined that the

test interval of 4,000 hours time-in-service, which will be recommended

by Boeing for inclusion in the next revision to the MRB report, is too

long in light of the sync lock function and the limited information

available to substantiate in-service experience of the sync lock.

Consequently, the FAA has based the requirement for accomplishment of

the test at intervals of 1,000 hours time-in-service, as specified in

paragraph (e) of this AD, on a philosophy that will ensure that all

affected operators will accomplish a common sync lock integrity test at

common intervals.

The FAA anticipates that when the revised MRB report is issued in

early 1994, that revision will contain a recommendation for

accomplishment of the sync lock integrity test that is consistent with

the requirements of paragraph (e) of this AD, thereby allowing the MRB

to be consistent with AD-required actions.

Several commenters request that the repetitive interval for

functional tests of the sync lock installation be increased from the

proposed 1,000 hours time-in-service to 3,000 hours time-in-service.

One commenter states that, according to results of a check of the sync

lock installation accomplished by Boeing, the proposed 1,000-hour

functional test was intended to be accomplished only on Model 767

series airplanes due to physical changes between the sync lock systems

installed on Model 757 and 767 series airplanes. One commenter reasons

that the proposed interval for functional tests of the sync lock device

should be 3,000 hours time-in-service because AD 91-20-09 (which will

be superseded by this proposed AD) specifies a 3,000-hour interval for

inspections and tests of the thrust reverser system.

The FAA does not concur with the commenters' request. The test

interval specified in this AD is reduced from the interval specified in

AD 91-20-09 because only limited information is available currently to

substantiate the in-service reliability of the sync lock device.

Consequently, the FAA has established an appropriate functional test

interval to ensure all affected operators will accomplish a common sync

lock integrity test at common intervals not to exceed 1,000 hours time-

in-service.

``Note 2'' of this final rule has been revised to state that

paragraph ``(c)'' of this AD restates the requirement for repetitive

inspections contained in paragraph (d) of AD 91-20-09, Amendment 39-

8043. An incorrect reference to paragraph ``(d)'' of this AD was made

in ``Note 2'' of the supplemental NPRM.

After careful review of the available data, including the comments

noted above, the FAA has determined that air safety and the public

interest require the adoption of the rule with the change previously

described. The FAA has determined that this change will neither

increase the economic burden on any operator nor increase the scope of

the AD.

There are approximately 211 Model 757 series airplanes of the

affected design in the worldwide fleet. The FAA estimates that 192

airplanes of U.S. registry will be affected by this AD, that it will

take approximately 624 work hours per airplane to accomplish the

required modification, and that the average labor rate is $55 per work

hour. Required parts will be supplied by the manufacturer at no cost to

operators. Based on these figures, the total cost impact of the AD on

U.S. operators to accomplish the required modification is estimated to

be $6,589,440, or $34,320 per airplane.

The FAA recognizes that the required modification (sync lock

installation) entails a large number of work hours to accomplish.

However, the 5-year compliance time specified in paragraph (d) of this

AD should allow ample time for the sync lock installation to be

accomplished coincidentally with scheduled major airplane inspection

and maintenance activities, thereby minimizing the costs associated

with special airplane scheduling.

In addition, the FAA estimates that 270 airplanes of U.S. registry

will be required to accomplish the periodic functional tests required

by this AD, that it will take approximately 1 work hour per airplane to

accomplish each functional test, and that the average labor rate is $55

per work hour. Based on these figures, the total cost impact of the AD

on U.S. operators to accomplish each functional test is estimated to be

$14,850, or $55 per airplane.

Based on these figures, the total cost impact of the AD on U.S.

operators is estimated to be $6,604,290. This total cost figure assumes

that no operator has yet accomplished the requirements of this AD.

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.

For the reasons discussed above, I certify that this action (1) is

not a ``significant regulatory action'' under Executive Order 12866;

(2) is not a ``significant rule'' under DOT Regulatory Policies and

Procedures (44 FR 11034, February 26, 1979); and (3) 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 final evaluation has been prepared for this action

and it is contained in the Rules Docket. A copy of it 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, Incorporation by

reference, 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 removing amendment 39-8043 (56 FR

46725, September 16, 1991), and by adding a new airworthiness directive

(AD), amendment 39-8792, to read as follows:

94-01-10 Boeing: Amendment 39-8792. Docket 92-NM-173-AD. Supersedes

AD 91-20-09, Amendment 39-8043.

Applicability: Model 757 series airplanes equipped with Pratt

and Whitney PW2000 series engines, certificated in any category.

Compliance: Required as indicated, unless accomplished

previously.

Note 1: Paragraphs (a) and (b) of this AD restate the

requirements of AD 91-20-09, Amendment 39-8043, paragraphs (a) and

(b). As allowed by the phrase, ``unless accomplished previously,''

if the requirements of AD 91-20-09 have been accomplished

previously, paragraphs (a) and (b) of this AD do not require those

actions to be repeated.

Note 2: Paragraph (c) of this AD restates the requirement for

repetitive inspections contained in paragraph (d) of AD 91-20-09,

Amendment 39-8043. Paragraph (c) of this AD requires that the first

inspection required by this AD must be performed within the

specified repetitive inspection interval after the last inspection

performed in accordance with paragraph (d) of AD 91-20-09.

To prevent deployment of a thrust reverser in flight and

subsequent reduced controllability of the airplane, accomplish the

following:

(a) Within 14 days after September 16, 1991 (the effective date

of AD 91-20-09, Amendment 39-8043), accomplish either paragraph

(a)(1) or (a)(2) of this AD.

(1) Accomplish both paragraphs (a)(1)(i) and (a)(1)(ii) of this

AD:

(i) Inspect the thrust reverser Directional Control Valve (DCV)

assemblies of both engines to determine the solenoid-driven pilot

valve's part number, in accordance with Boeing Alert Service

Bulletin 757-78A0027, dated September 9, 1991.

(A) If any DCV has a suspect pilot valve as specified in the

service bulletin, prior to further flight, replace the DCV with a

DCV that has a part number of a non-suspect solenoid-driven pilot

valve, in accordance with the service bulletin.

(B) If a DCV has a non-suspect solenoid-driven pilot valve as

specified in the service bulletin, that pilot valve does not need to

be replaced.

(ii) Perform all tests and inspections of the engine thrust

reverser control and indication system on both engines in accordance

with Boeing Service Bulletin 757-78-0025, dated September 9, 1991.

Prior to further flight, correct any discrepancy found in accordance

with the service bulletin.

(2) Accomplish paragraph (a)(1) of this AD on one engine's

thrust reverser and deactivate the other engine's thrust reverser,

in accordance with section 78-31-1 of Boeing Document D630N002,

``Boeing 757 Dispatch Deviation Guide,'' Revision 8, dated January

15, 1991.

(b) Within 24 days after September 16, 1991 (the effective date

of AD 91-20-09, Amendment 39-8043), the requirements of paragraph

(a)(1) of this AD must be accomplished on both engines' thrust

reverser systems.

(c) Repeat the tests and inspections specified in paragraph

(a)(1)(ii) at intervals not to exceed 3,000 flight hours, and prior

to further flight following any maintenance that disturbs the thrust

reverser control system. Prior to further flight, correct any

discrepancy found in accordance with Boeing Service Bulletin 757-78-

0025, dated September 9, 1991.

(d) Within 5 years after the effective date of this AD, install

an additional thrust reverser system locking feature (sync lock

installation), in accordance with Boeing Service Bulletin 757-78-

0028, Revision 1, dated October 29, 1992, or Revision 2, dated

January 14, 1993.

(e) Within 1,000 hours time-in-service after installing the sync

lock required by paragraph (d) of this AD (either in production or

by retrofit), or within 1,000 hours time-in-service after the

effective date of this AD, whichever occurs later; and thereafter at

intervals not to exceed 1,000 hours time-in-service: Perform

functional tests of the sync lock in accordance with the ``Thrust

Reverser Sync Lock Integrity Test'' procedures specified below. If

any discrepancy is found during any test, prior to further flight,

correct it in accordance with procedures described in the Boeing 757

Maintenance Manual.

``Thrust Reverser Sync Lock Integrity Test

1. General

A. Use this procedure to test the integrity of the thrust

reverser sync locks.

2. Thrust Reverser Sync Lock Test

A. Prepare for the Thrust Reverser Sync Lock Test.

(1) Open the AUTO SPEEDBRAKE circuit breaker on the overhead

circuit breaker panel, P11.

(2) Do the steps that follow to supply power to the thrust

reverser system:

(a) Make sure the thrust levers are in the idle position.

Caution: Do not extend the thrust reverser while the core cowl

panels are open. Damage to the thrust reverser and core cowl panels

can occur.

(b) Make sure the thrust reverser halves are closed.

(c) Make sure the core cowl panels are closed.

(d) Put the EEC maint power switch or the EEC power L and EEC

power R switches to the Altn position.

(e) For the left engine:

(1) Put the EEC MAINT CHANNEL SEL L switch to the AUTO position.

(2) Put the L ENG fire switch to the NORM position.

(f) For the right engine:

(1) Put the EEC MAINT CHANNEL SEL R switch to the AUTO position.

(2) Put the R ENG fire switch to the NORM position.

(g) Make sure the EICAS circuit breakers (6 locations) are

closed.

Warning: The thrust reverser will automatically retract if the

electrical power to the EEC/thrust reverser control system is turned

off or if the EEC maint power switch is moved to the norm position.

The accidental operation of the thrust reverser can cause injury to

persons or damage to equipment can occur.

(h) Make sure these circuit breakers on the main power

distribution panel, P6, are closed:

(1) Fuel cond cont L

(2) Fuel cond cont R

(3) T/L interlock L

(4) T/L interlock R

(5) Left T/R sync lock

(6) Right T/R sync lock

(7) L eng electronic engine control altn pwr (if installed)

(8) R eng electronic engine control altn pwr (if installed)

(i) Make sure these circuit breakers on the overhead circuit

breaker panel, P11, are closed:

(1) Air/gnd sys 1

(2) Air/gnd sys 2

(3) Landing gear pos sys 1

(4) Landing gear pos sys 2

(j) For the left engine, make sure these circuit breakers on the

P11 panel are closed:

(1) Left engine pdiu

(2) Left engine thrust reverser cont/scav press

(3) Left engine electronic engine control altn pwr (if

installed)

(4) Left engine thrust reverser pri cont

(5) Left engine thrust reverser sec cont

(k) For the right engine, make sure these circuit breakers on

the P11 panel are closed:

(1) Right engine pdiu

(2) Right engine thrust reverser cont/scav press

(3) Right engine electronic engine control altn pwr (if

installed)

(4) Right engine thrust reverser pri cont

(5) Right engine thrust reverser sec cont

(l) Supply electrical power.

(m) Remove the pressure from the left (right) hydraulic system.

B. Do the Thrust Reverser Sync Lock Test.

(1) Move and hold the manual unlock lever on the center actuator

on both thrust reverser sleeves to the unlock position.

(2) Make sure the thrust reverser sleeves did not move.

(3) Move the left (right) reverser thrust lever up and rearward

to the idle detent position.

(4) Make sure both thrust reverser sleeves move aft

(approximately 0.15 to 0.25 inch).

(5) Release the manual unlock lever on the center actuators.

Warning: Make sure all persons and equipment are clear of the

area around the thrust reverser. When you apply hydraulic pressure

the thrust reverser will extend and can cause injuries to persons or

damage to equipment.

(6) Pressurize the left (right) hydraulic system.

(7) Make sure the thrust reverser extends.

(8) Move the left (right) reverser thrust lever to the fully

forward and down position to retract the thrust reverser.

C. Put the Airplane Back to its Usual Condition.

(1) Remove hydraulic pressure.

(2) Close the left and right fan cowls.

(3) Close the AUTO SPEEDBRAKE circuit breaker on the P11 panel.

(4) Remove electrical power if it is not necessary.

D. Repeat the Thrust Reverser Sync Lock Test on the other

engine.''

(f) Installation of the sync lock, as required by paragraph (d)

of this AD, constitutes terminating action for the requirements of

paragraphs (a) through (c) of this AD.

(g) 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, Seattle 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, Seattle ACO.

Note 3: Approvals of alternative methods of compliance issued

for AD 91-20-09 constitute valid approvals for compliance with the

requirements of paragraphs (a) through (c) of this AD.

Note 4: Information concerning the existence of approved

alternative methods of compliance with this AD, if any, may be

obtained from the Seattle ACO.

(h) Special flight permits may be issued in accordance with FAR

21.197 and 21.199 to operate the airplane to a location where the

requirements of this AD can be accomplished.

(i) The actions shall be done in accordance with Boeing Alert

Service Bulletin 757-78A0027, dated September 9, 1991; Boeing

Service Bulletin 757-78-0025, dated September 9, 1991; Boeing

Document D630N002, ``Boeing 757 Dispatch Deviation Guide,'' Revision

8, dated January 15, 1991; Boeing Service Bulletin 757-78-0028,

Revision 1, dated October 29, 1992; and Boeing Service Bulletin 757-

78-0028, Revision 2, dated January 14, 1993. The incorporation by

reference of Boeing Alert Service Bulletin 757-78A0027, dated

September 9, 1991; Boeing Service Bulletin 757-78-0025, dated

September 9, 1991; Boeing Document D630N002, ``Boeing 757 Dispatch

Deviation Guide,'' Revision 8, dated January 15, 1991; was approved

previously by the Director of the Federal Register in accordance

with 5 U.S.C. 552(a) and 1 CFR part 51 as of September 16, 1991 (56

FR 46725, September 16, 1991). The incorporation by reference of the

remainder of the service documents listed above is approved by the

Director of Federal Register in accordance with 5 U.S.C. 552(a) and

1 CFR part 51. Copies may be obtained from Boeing Commercial

Airplane Group, P.O. Box 3707, Seattle, Washington 98124-2207.

Copies may be inspected at the FAA, Transport Airplane Directorate,

1601 Lind Avenue, SW., Renton, Washington; or at the Office of the

Federal Register, 800 North Capitol Street, NW., suite 700,

Washington, DC.

(j) This amendment becomes effective on March 3, 1994.

Issued in Renton, Washington, on January 3, 1994.

Darrell M. Pederson,

Acting Manager, Transport Airplane Directorate, Aircraft Certification

Service.

[FR Doc. 94-346 Filed 1-31-94; 8:45 am]

BILLING CODE 4910-13-P