Airworthiness Directives; Boeing Model 747 and 757 Series Airplanes

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

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

Transport Airplane Directorate, 1601 Lind Avenue, SW., Renton,

Washington.

FOR FURTHER INFORMATION CONTACT: G. Michael Collins, Aerospace

Engineer, Seattle Aircraft Certification Office, Propulsion Branch,

ANM-140S, FAA, Transport Airplane Directorate, 1601 Lind Avenue, SW.,

Renton, Washington 98055-4056; telephone (206) 227-2689; fax (206) 227-

1181.

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 96-NM-57-AD.'' The postcard will be date stamped and

returned to the commenter.

Availability of NPRMs

ith

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 96-NM-57-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. 96-NM-57-AD, 1601 Lind Avenue, SW., Renton, Washington

98055-4056.

Discussion

The FAA has received several reports of fuel leaks at the fuel

boost and override/jettison pumps on Boeing Model 747 series airplanes.

As a result of these incidents, the fuel pumps were removed from these

airplanes. These pumps had accumulated between 34,000 to 67,000 total

hours since new or since overhaul.

Analyses of the removed pumps revealed that moisture ingression

around the potting of the wire terminal assembly can cause corrosion in

the wire terminal assembly. (Variation in the manufacturing of the

connectors and exposure of an airplane to different operational

environments can affect the time required to form the corrosion.) Such

corrosion can lead to electrical arcing between the power pins and the

pump case. The arcing could then cause deterioration of the terminal

pins and thermal expansion of the material inside the cap. Thermal

expansion can cause failure of the cap attachment flange or attaching

screws, and, consequently lead to a fuel leak. A high current during

arcing also could melt a hole through the end case and connector of the

fuel pump, which also could result in a fuel leak.

Fuel leakage at the fuel boost and override/jettison pumps, if not

detected and corrected, could result in a fire at the location of the

affected fuel pump

lure of the cap attachment flange or attaching

screws, and, consequently lead to a fuel leak. A high current during

arcing also could melt a hole through the end case and connector of the

fuel pump, which also could result in a fuel leak.

Fuel leakage at the fuel boost and override/jettison pumps, if not

detected and corrected, could result in a fire at the location of the

affected fuel pump.

The fuel boost and override/jettison pumps of Model 747 series

airplanes are similar in design to those of Model 757 series airplanes.

Therefore, the FAA has determined that Model 757 series airplanes may

be subject to the same fuel leakage problem.

Explanation of Relevant Service Information

The FAA has reviewed and approved Boeing Service Bulletin 747-

28A2194, Revision 1, dated January 18, 1996 (for Model 747 series

airplanes), and Boeing Service Bulletin 757-28A0043, Revision 1, dated

January 18, 1996 (for Model 757 series airplanes). These service

bulletins describe procedures for repetitive visual inspections to

detect discrepancies (i.e., fuel leak, heat discoloration, and damage)

of the wire terminal assembly, electrical connector, and wire

insulation on the fuel pump; and replacement of the fuel pump with a

new fuel pump, if necessary. These service bulletins also describe

procedures for repetitive insulation resistance tests of the fuel pump

wiring.

Explanation of Requirements of Proposed Rule

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 a visual inspection to detect discrepancies

of the wire terminal assembly, electrical connector, and wire

insulation on the fuel pump; and replacement of the fuel pump with a

new fuel pump, if necessary. The proposed AD also would require

repetitive insulation resistance tests of the fuel pump wiring. The

actions would be required to be accomplished in accordance with the

service bulletins described previously.

Interim Action

pancies

of the wire terminal assembly, electrical connector, and wire

insulation on the fuel pump; and replacement of the fuel pump with a

new fuel pump, if necessary. The proposed AD also would require

repetitive insulation resistance tests of the fuel pump wiring. The

actions would be required to be accomplished in accordance with the

service bulletins described previously.

Interim Action

This is considered to be interim action until final action is

identified, at which time the FAA may consider further rulemaking.

Cost Impact

There are approximately 1,084 Model 747 series airplanes and 716

Model 757 series airplanes of the affected design in the worldwide

fleet. Of these airplanes, 242 Model 747 series airplanes and 462 Model

757 series airplanes are of U.S. registry and would be affected by this

proposed AD.

For 242 Model 747 series airplanes, it would take approximately 18

work hours per airplane to accomplish the proposed actions, at an

average labor rate of $60 per work hour. Based on these figures, the

cost impact of the proposed AD on U.S. operators of Model 747 series

airplanes is estimated to be $261,360, or $1,080 per airplane.

For the 462 Model 757 series airplanes, it would take approximately

12 work hours per airplane to accomplish the proposed actions, at an

average labor rate of $60 per work hour. Based on these figures, the

cost impact of the proposed AD on U.S. operators of Model 757 series

airplanes is estimated to be $332,640, or $720 per airplane.

The cost impact figures discussed above 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.

Regulatory Impact

t impact of the proposed AD on U.S. operators of Model 757 series

airplanes is estimated to be $332,640, or $720 per airplane.

The cost impact figures discussed above 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.

Regulatory Impact

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]

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:

Boeing: Docket 96-NM-57-AD.

Applicability: All Model 747 and 757 series airplanes,

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 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 (c) 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 fuel leakage at the fuel boost and override/jettison

pumps, which could result in a fire at the location of the affected

fuel pump, accomplish the following:

e 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 fuel leakage at the fuel boost and override/jettison

pumps, which could result in a fire at the location of the affected

fuel pump, accomplish the following:

(a) Within 120 days after the effective date of this AD, perform

a visual inspection to detect discrepancies (i.e., fuel leak, heat

discoloration, and damage) of the wire terminal assembly, electrical

connector, and wire insulation on the fuel pump, in accordance with

Boeing Service Bulletin 747-28A2194, Revision 1, dated January 18,

1996 (for Model 747 series airplanes), or Boeing Service Bulletin

757-28A0043, Revision 1, dated January 18, 1996 (for Model 757

series airplanes), as applicable.

(1) If no discrepancy is detected, prior to further flight,

perform an insulation resistance test of the fuel pump wiring, in

accordance with the Accomplishment Instructions of the applicable

service bulletin.

(i) If any resistance measurement is less than or equal to 1

megohms, prior to further flight, replace the fuel pump with a new

fuel pump, in accordance with the applicable service bulletin. Prior

to further flight following accomplishment of the replacement,

repeat the insulation resistance test.

(ii) If any resistance measurement is greater than 1 megohms but

less than 5 megohms: Repeat the visual inspection and insulation

resistance test within 500 hours, or replace the fuel pump with a

new fuel pump. Prior to further flight following accomplishment of

the replacement, repeat the insulation resistance test.

(iii) If any resistance measurement is greater than or equal to

5 megohms, repeat the visual inspection and insulation resistance

test within 5,000 hours or 18 months, whichever occur first.

and insulation

resistance test within 500 hours, or replace the fuel pump with a

new fuel pump. Prior to further flight following accomplishment of

the replacement, repeat the insulation resistance test.

(iii) If any resistance measurement is greater than or equal to

5 megohms, repeat the visual inspection and insulation resistance

test within 5,000 hours or 18 months, whichever occur first.

(2) If any discrepancy is detected, prior to further flight,

replace the fuel pump with a new fuel pump, in accordance with the

applicable service bulletin. Prior to further flight following

accomplishment of the replacement, perform an insulation resistance

test of the fuel pump wiring, in accordance with the Accomplishment

Instructions of the applicable service bulletin.

(i) If any resistance measurement is less than or equal to 1

megohms, prior to further flight, replace the fuel pump with a new

fuel pump, in accordance with the applicable service bulletin. Prior

to further flight following accomplishment of the replacement,

repeat the insulation resistance test.

(ii) If any resistance measurement is greater than 1 megohms but

less than 5 megohms: Repeat the visual inspection and insulation

resistance test within 500 hours, or replace the fuel pump with a

new fuel pump. Prior to further flight following accomplishment of

the replacement, repeat the insulation resistance test.

(iii) If any resistance measurement is greater than or equal to

5 megohms, repeat the visual inspection and insulation resistance

test within 5,000 hours or 18 months, whichever occur first.

and insulation

resistance test within 500 hours, or replace the fuel pump with a

new fuel pump. Prior to further flight following accomplishment of

the replacement, repeat the insulation resistance test.

(iii) If any resistance measurement is greater than or equal to

5 megohms, repeat the visual inspection and insulation resistance

test within 5,000 hours or 18 months, whichever occur first.

(b) Within 10 days after accomplishing the initial visual

inspection required by paragraph (a) of this AD, submit a report of

the inspection results (both positive and

negative findings) to the Manager, Seattle Aircraft Certification

Office (ACO), 1601 Lind Avenue, SW., Renton, Washington 98055-4056;

telephone (206) 227-2689; fax (206) 227-1181. Information collection

requirements contained in this regulation have been approved by the

Office of Management and Budget (OMB) under the provisions of the

Paperwork Reduction Act of 1980 (44 U.S.C. 3501 et seq.) and have

been assigned OMB Control Number 2120-0056.

(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, 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 2: Information concerning the existence of approved

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

obtained from the Seattle ACO.

le 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 2: Information concerning the existence of approved

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

obtained from the Seattle ACO.

(d) 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 August 7, 1996.

Darrell M. Pederson,

Acting Manager, Transport Airplane Directorate, Aircraft Certification

Service.

[FR Doc. 96-20671 Filed 8-13-96; 12:33 pm]

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