Airworthiness Directives; Boeing Model 737-100, -200, -300, -400, and -500 Series Airplanes

DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 98-NM-318-AD]

RIN 2120-AA64

Airworthiness Directives; Boeing Model 737-100, -200, -300, -400,

and -500 Series Airplanes

AGENCY: Federal Aviation Administration, DOT.

ACTION: Notice of proposed rulemaking (NPRM).

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SUMMARY: This document proposes the supersedure of an existing

airworthiness directive (AD), applicable to all Boeing Model 737-100, -

200, -300, -400, and -500 series airplanes, that currently requires

removal of the fuel boost pump wiring in the conduits of the wing and

center fuel tanks; an inspection to detect damage of the wiring, and

corrective action, if necessary; and eventual installation of Teflon

sleeving over the electrical cable. This action would expand the

inspection requirement to include additional airplanes, add repetitive

inspections for all airplanes, and reidentify the requirement to

install Teflon sleeving as a nonterminating action. This proposal is

prompted by the FAA's determination that Model 737-100 through -500

series airplanes that are not affected by the current AD must also be

protected against excessive wire chafing of the fuel boost pump wiring

and that all affected airplanes must be repetitively inspected. The

actions specified by the proposed AD are intended to detect and correct

chafing and prevent electrical arcing between the fuel boost pump

wiring and the surrounding conduit, which could result in arc-through

of the conduit, and consequent fire or explosion of the fuel tank.

DATES: Comments must be received by February 25, 1999.

ADDRESSES: Submit comments in triplicate to the Federal Aviation

Administration (FAA), Transport Airplane Directorate, ANM-114,

Attention: Rules Docket No. 98-NM-318-AD, 1601 Lind Avenue, SW.,

Renton, Washington 98055-4056.

[[Page 1546]]

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 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: Dorr Anderson, Aerospace Engineer,

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

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

Washington 98055-4056; telephone (425) 227-2684; fax (425) 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 98-NM-318-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-114, Attention: Rules

Docket No. 98-NM-318-AD, 1601 Lind Avenue, SW., Renton, Washington

98055-4056.

Discussion

On September 23, 1998, the FAA issued AD 98-19-09, amendment 39-

10751 (63 FR 52152, September 30, 1998), applicable to all Boeing Model

737-100, -200, -300, -400, and -500 series airplanes, to require

removal of the fuel boost pump wiring in the conduits of the wing and

center fuel tanks; an inspection to detect damage of the wiring, and

corrective action, if necessary; and eventual installation of Teflon

sleeving over the electrical cable. The actions of that AD were

required for airplanes that had accumulated 20,000 or more total flight

hours. That AD was prompted by reports of severe wear of the fuel boost

pump wiring due to chafing between the wiring and the surrounding

conduit inside the fuel tank; pin-hole-sized holes in the conduit that

appear to be the result of arc-through of the conduit; and exposure of

the main tank boost pump wire conductor inside a conduit and signs of

arcing to the wall of the conduit. The requirements of that AD are

intended to detect and correct chafing and electrical arcing between

the fuel boost pump wiring and the surrounding conduit, which, if not

corrected, could result in arc-through of the conduit, and consequent

fire or explosion of the fuel tank.

Actions Since Issuance of Previous Rule

In the preamble to AD 98-19-09, the FAA indicated it was

considering further rulemaking action to require inspection of Model

737 series airplanes that have accumulated less than 20,000 total

flight hours. The FAA now has determined that further rulemaking action

is indeed necessary, and this proposed AD follows from that

determination. The FAA has determined that it is necessary to expand

the inspection requirement to ensure that excessive wire chafing does

not occur on those airplanes.

The FAA has examined wire bundles that were removed and inspected

for chafing in accordance with telegraphic AD's T98-10-51 (issued on

May 7, 1998) and T98-11-51 (issued on May 10, 1998) and AD 98-11-52 (63

FR 34271, June 24, 1998). Based on the findings, the FAA tabulated

levels of wire chafing as a function of airplane flight hours. Based on

the tabulated data, the FAA has determined that it is necessary to

define long-term repetitive inspection intervals to address the

identified unsafe condition for the entire fleet of 737-100 through -

500 series airplanes. In consideration of these data and the additional

layer of Teflon sleeving installed for further protection of the wire

bundles, the FAA proposes a repetitive inspection interval of 30,000

flight hours.

In light of the new proposed repetitive inspections, the

installation of Teflon sleeving required by AD 98-19-09, which

terminates the requirements of that AD, would not terminate the

requirements of this proposed AD.

Explanation of Relevant Service Information

The FAA has reviewed and approved Boeing Service Bulletin 737-

28A1120,

Revision 2, dated November 26, 1998. The procedures described in

Revision 2 of this service bulletin are essentially identical to those

described in Boeing Alert Service Bulletin 737-28A1120, Revision 1,

dated May 28, 1998 (which was referenced as an appropriate source of

service information in AD 98-19-09). Revision 2 removes certain

airplanes from the effectivity listing and specifies different parts to

be provided in the parts kit by the manufacturer. Accomplishment of the

actions specified in the service bulletin is intended to adequately

address the identified unsafe condition.

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 supersede AD 98-19-09 to continue to require removal

of the fuel boost pump wiring in the conduits of the wing and center

fuel tanks; an inspection to detect damage of the wiring, and

corrective action, if necessary; and eventual installation of Teflon

sleeving over the electrical cable. This action would additionally

require that the inspection be conducted at repetitive intervals and

that the inspection be accomplished on airplanes that have accumulated

less than 20,000 total flight hours. The actions would be required to

be accomplished in accordance with the service bulletin described

previously, except as discussed below. The proposed AD also would

require that operators report results of the initial inspection to the

FAA.

Difference Between the Proposed AD and the Service Bulletin

Operators should note that, while Boeing Service Bulletin 737-

28A1120, Revision 2, limits its effectivity to airplanes having line

numbers 1 through 3072 inclusive, this proposed AD would be applicable

to all Model 737-100 through -500 series airplanes.

[[Page 1547]]

Cost Impact

There are approximately 2,866 airplanes of the affected design in

the worldwide fleet. The FAA estimates that 1,131 airplanes of U.S.

registry would be affected by this proposed AD.

The inspection that is currently required by AD 98-19-09, and

retained in this AD, takes approximately 30 work hours per airplane to

accomplish, at an average labor rate of $60 per work hour. This new AD

action would require repetitive performance of that inspection. Based

on these figures, the cost impact of the proposed AD on U.S. operators

is estimated to be $2,035,800, or $1,800 per airplane, per inspection

cycle.

The cost impact figure discussed above is based on assumptions that

no operator has yet accomplished any of the current or 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]

2. Section 39.13 is amended by removing amendment 39-10751 (63 FR

52152, September 30, 1998), and by adding a new airworthiness directive

(AD), to read as follows:

Boeing: Docket 98-NM-318-AD. Supersedes AD 98-19-09, Amendment 39-

10751.

Applicability: All Model 737-100, -200, -300, -400, and -500

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 (n)(1)

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 detect and correct chafing and prevent electrical arcing

between the fuel boost pump wiring and the surrounding conduit,

which could result in arc-through of the conduit, and consequent

fire or explosion of the fuel tank, accomplish the following:

Inspections Required by AD 98-11-52

(a) For all airplanes that have accumulated 50,000 or more total

flight hours as of June 29, 1998 (the effective date of AD 98-11-52,

amendment 39-10611): Prior to further flight, remove the fuel boost

pump wiring from the in-tank conduit for the aft boost pumps in main

tanks numbers 1 and 2, and perform a detailed visual inspection to

detect damage of the wiring, in accordance with the procedures

specified in Boeing Alert Service Bulletin 737-28A1120, dated April

24, 1998, as revised by Notices of Status Change NSC 01, dated May

7, 1998, NSC 02, dated May 8, 1998, and NSC 03, dated May 9, 1998;

Boeing Alert Service Bulletin 737-28A1120, Revision 1, dated May 28,

1998; or Boeing Service Bulletin 737-28A1120, Revision 2, dated

November 26, 1998.

(b) For all airplanes that have accumulated less than 50,000

total flight hours as of receipt of telegraphic AD T98-11-51: Prior

to the accumulation of 40,000 total flight hours, or within 14 days

after June 29, 1998, whichever occurs later, remove the fuel boost

pump wiring from the in-tank conduit for the aft boost pumps in main

tanks numbers 1 and 2, and perform a detailed visual inspection to

detect damage of the wiring, in accordance with the procedures

specified in Boeing Alert Service Bulletin 737-28A1120, dated April

24, 1998, as revised by Notices of Status Change NSC 01, dated May

7, 1998, NSC 02, dated May 8, 1998, and NSC 03, dated May 9, 1998;

Revision 1, dated May 28, 1998; or Revision 2, dated November 26,

1998.

(c) For all airplanes: Remove the fuel boost pump wiring from

the in-tank conduit for the center tank left and right boost pumps,

and perform a detailed visual inspection to detect damage of the

wiring, in accordance with the procedures specified in Boeing Alert

Service Bulletin 737-28A1120, dated April 24, 1998, as revised by

Notices of Status Change NSC 01, dated May 7, 1998, NSC 02, dated

May 8, 1998, and NSC 03, dated May 9, 1998; Revision 1, dated May

28, 1998; or Revision 2, dated November 26, 1998. Accomplish the

inspection at the earliest of the times specified in paragraphs

(c)(1), (c)(2), and (c)(3).

(1) For Model 737-300, -400, and -500 series airplanes: Inspect

prior to the accumulation of 40,000 total flight hours, or within 14

days after June 29, 1998, whichever occurs later.

(2) For Model 737-100 and -200 series airplanes: Inspect prior

to the accumulation of 40,000 total flight hours, or within 10 days

after June 29, 1998, whichever occurs later.

(3) For all airplanes: Inspect prior to the accumulation of

50,000 total flight hours, or within 5 days after June 29, 1998,

whichever occurs later.

(d) For all airplanes: Prior to the accumulation of 30,000 total

flight hours or within 45 days after June 29, 1998, whichever occurs

later, remove the fuel boost pump wiring from the in-tank conduit

for the aft boost pumps in main tanks numbers 1 and 2, and the

center tank left and right boost pumps, and perform a detailed

visual inspection to detect damage of the wiring, in accordance with

the procedures specified in Boeing Alert Service Bulletin 737-

28A1120, dated April 24, 1998, as revised by Notices of Status

Change NSC 01, dated May 7, 1998, NSC 02, dated May 8, 1998, and NSC

03, dated May 9, 1998; Revision 1, dated May 28, 1998; or Revision

2, dated November 26, 1998.

Inspection Required by AD 98-19-09

(e) For airplanes that have accumulated 20,000 or more total

flight hours and less than 30,000 total flight hours as of October

15, 1998 (the effective date of AD 98-19-09, amendment 39-10751):

Within 60 days after October 15, 1998, remove the fuel boost pump

wiring from the in-tank conduit for the aft boost pumps in main

tanks numbers 1 and 2, and the center tank left and right boost

pumps, and perform a detailed visual inspection to detect damage of

the wiring; in accordance with the procedures specified in Boeing

Alert Service Bulletin 737-28A1120, dated April 24, 1998, as revised

by Notices of Status Change NSC 01, dated May 7, 1998, NSC 02, dated

May 8, 1998, and NSC 03, dated May 9, 1998; Revision 1, dated May

28, 1998; or Revision 2, dated November 26, 1998.

New Inspection Requirements

(f) For airplanes that have accumulated less than 20,000 total

flight hours as of October

[[Page 1548]]

15, 1998: Remove the fuel boost pump wiring from the in-tank conduit

for the aft boost pumps in main tanks numbers 1 and 2, and the

center tank left and right boost pumps, and perform a detailed

visual inspection to detect damage of the wiring; at the earlier of

the times specified in paragraphs (f)(1) and (f)(2) of this AD; in

accordance with the procedures specified in Boeing Alert Service

Bulletin 737-28A1120, dated April 24, 1998, as revised by Notices of

Status Change NSC 01, dated May 7, 1998, NSC 02, dated May 8, 1998,

and NSC 03, dated May 9, 1998; Boeing Alert Service Bulletin 737-

28A1120, Revision 1, dated May 28, 1998; or Boeing Service Bulletin

737-28A1120, Revision 2, dated November 26, 1998.

(1) Prior to the accumulation of 20,000 total flight hours, or

within 60 days after the effective date of this AD, whichever occurs

later.

(2) Within 24 months after the effective date of this AD.

(g) For all airplanes: Repeat the inspection required by

paragraph (d), (e), or (f) of this AD, as applicable, at intervals

not to exceed 30,000 flight hours after initial accomplishment of

the applicable inspection.

Corrective Actions

(h) If red, yellow, blue, or green wire insulation cannot be

seen through the outer jacket of the electrical cable during any

inspection required by this AD: Prior to further flight, accomplish

paragraph (h)(1), (h)(2), or (h)(3) of this AD in accordance with

procedures specified in Boeing Alert Service Bulletin 737-28A1120,

dated April 24, 1998, as revised by Notices of Status Change NSC 01,

dated May 7, 1998, NSC 02, dated May 8, 1998, and NSC 03, dated May

9, 1998; Revision 1, dated May 28, 1998; or Revision 2, dated

November 26, 1998.

(1) Install Teflon sleeving over the electrical cable, and

reinstall the cable. Or

(2) Reinstall the electrical cable without Teflon sleeving over

the cable. Within 500 flight hours after accomplishment of the

reinstallation, repeat the inspection described in paragraph (d),

(e), or (f) of this AD, as applicable, and install Teflon sleeving

over the cable. Or

(3) Replace the electrical cable with new cable without Teflon

sleeving. Within 18 months or 6,000 flight hours, whichever occurs

first, repeat the inspection specified in paragraph (d), (e), or (f)

of this AD, as applicable, and install Teflon sleeving over the

cable.

(i) If red, yellow, blue, or green wire insulation can be seen

through the outer jacket of the electrical cable during any

inspection required by this AD, but no evidence of electrical arcing

is found: Prior to further flight, accomplish either paragraph

(i)(1) or (i)(2) of this AD in accordance with the procedures

specified in Boeing Alert Service Bulletin 737-28A1120, dated April

24, 1998, as revised by Notices of Status Change NSC 01, dated May

7, 1998, NSC 02, dated May 8, 1998, and NSC 03, dated May 9, 1998;

Boeing Alert Service Bulletin 737-28A1120, Revision 1, dated May 28,

1998; or Boeing Service Bulletin 737-28A1120, Revision 2, dated

November 26, 1998.

(1) Replace the damaged electrical cable with a new cable,

install Teflon sleeving over the cable, and reinstall the cable. Or

(2) Replace the electrical cable with a new cable without Teflon

sleeving. Within 18 months or 6,000 flight hours, whichever occurs

first, repeat the inspection described in paragraph (d), (e), or (f)

of this AD, as applicable, and install Teflon sleeving over the

cable.

(j) If any evidence of electrical arcing but no evidence of fuel

leakage is found on the removed electrical cable during any

inspection required by this AD: Prior to further flight, accomplish

paragraphs (j)(1) and (j)(2) of this AD in accordance with the

procedures specified in Boeing Alert Service Bulletin 737-28A1120,

dated April 24, 1998, as revised by Notices of Status Change NSC 01,

dated May 7, 1998, NSC 02, dated May 8, 1998, and NSC 03, dated May

9, 1998; Boeing Alert Service Bulletin 737-28A1120, Revision 1,

dated May 28, 1998; or Boeing Service Bulletin 737-28A1120, Revision

2, dated November 26, 1998.

(1) Verify the integrity of the conduit in accordance with the

instructions contained in NSC 03, Revision 1, or Revision 2 of the

alert service bulletin. And

(2) Accomplish either paragraph (j)(2)(i) or (j)(2)(ii) of this

AD in accordance with the alert service bulletin.

(i) Replace the damaged electrical cable with a new cable,

install Teflon sleeving over the cable, and reinstall the cable. Or

(ii) Replace the electrical cable with a new cable without

Teflon sleeving. Within 18 months or 6,000 flight hours, whichever

occurs first, repeat the inspection described in paragraph (d), (e),

or (f) of this AD, as applicable, and install Teflon sleeving over

the cable.

(k) If any evidence of fuel is found on the removed electrical

cable during any inspection required by this AD: Prior to further

flight, accomplish paragraphs (k)(1) and (k)(2) of this AD in

accordance with the procedures specified in Boeing Alert Service

Bulletin 737-28A1120, dated April 24, 1998, as revised by Notices of

Status Change NSC 01, dated May 7, 1998, NSC 02, dated May 8, 1998,

and NSC 03, dated May 9, 1998; Boeing Alert Service Bulletin 737-

28A1120, Revision 1, dated May 28, 1998; or Boeing Service Bulletin

737-28A1120, Revision 2, dated November 26, 1998.

(1) Replace the conduit section where electrical arcing was

found. And

(2) Accomplish either paragraph (k)(2)(i) or (k)(2)(ii) of this

AD.

(i) Replace the damaged electrical cable with a new cable,

install Teflon sleeving over the cable, and reinstall the cable. Or

(ii) Replace the electrical cable with a new cable without

Teflon sleeving. Within 18 months or 6,000 flight hours, whichever

occurs first, repeat the inspection described in paragraph (d), (e),

or (f) of this AD, as applicable, and install Teflon sleeving over

the cable.

(l) For Groups 1 and 2 airplanes, as identified in Boeing Alert

Service Bulletin 737-28A1120, dated April 24, 1998: Concurrent with

the first accomplishment of corrective action in accordance with

paragraph (h), (i), (j), or (k) of this AD, as applicable, replace

the case ground wire with a new wire in accordance with Boeing Alert

Service Bulletin 737-28A1120, dated April 24, 1998, as revised by

Notices of Status Change NSC 01, dated May 7, 1998, NSC 02, dated

May 8, 1998, and NSC 03, dated May 9, 1998; Boeing Alert Service

Bulletin 737-28A1120, Revision 1, dated May 28, 1998; or Boeing

Service Bulletin 737-28A1120, Revision 2, dated November 26, 1998.

(m) If any damage specified in paragraph (h), (i), or (j) of

this AD is found during the initial inspection required by paragraph

(a), (b), (c), (d), (e), or (f) of this AD, as applicable: Within 10

days after accomplishing that initial inspection, accomplish

paragraphs (m)(1) and (m)(2) of this AD. 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.

(1) Submit any damaged electrical cables and conduits to Boeing,

in accordance with Boeing Alert Service Bulletin 737-28A1120, dated

April 24, 1998, as revised by Notices of Status Change NSC 01, dated

May 7, 1998, NSC 02, dated May 8, 1998, and NSC 03, dated May 9,

1998; Boeing Alert Service Bulletin 737-28A1120, Revision 1, dated

May 28, 1998; or Boeing Service Bulletin 737-28A1120, Revision 2,

dated November 26, 1998. Include the serial number of the airplane,

the number of total flight hours and flight cycles accumulated on

the airplane, and the location of the electrical cable on the

airplane.

(2) For airplanes that are inspected after June 29, 1998, submit

the serial number of the airplane, the number of total flight hours

and flight cycles accumulated on the airplane, and the location of

the electrical cable on the airplane to the Manager, Seattle

Aircraft Certification Office (ACO), FAA, Transport Airplane

Directorate, 1601 Lind Avenue, SW., Renton, Washington 98055-4056;

fax (425) 227-1181.

(n)(1) 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.

(n)(2) Alternative methods of compliance, approved previously in

accordance with AD 98-11-52 and AD 98-19-09, are approved as

alternative methods of compliance with this AD.

Note 2: Information concerning the existence of approved

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

obtained from the Seattle ACO.

(o) 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.

[[Page 1549]]

Issued in Renton, Washington, on December 31, 1998.

Darrell M. Pederson,

Acting Manager, Transport Airplane Directorate, Aircraft Certification

Service.

[FR Doc. 99-482 Filed 1-8-99; 8:45 am]

BILLING CODE 4910-13-U