Federal Register / Vol. 73, No. 185 / Tuesday, September 23, 2008 / Proposed Rules 54751 

(NPA) 2002–043. The identified noncompliances were assessed using Transport 

Canada Policy Letter No. 525–001 to 

determine if mandatory corrective action was 

required. 

The assessment showed that due to the 

close proximity of intrinsically safe fuel 

system wiring with other wiring, a single 

failure from wire chafing at various locations 

of the fuselage could result in an ignition 

source inside the fuel tank. In addition, 

chafing of the temperature sensor wiring 

against the high power wiring in the avionics 

compartment could lead to overheating of the 

temperature sensor and hot surface ignition. 

The presence of an ignition source inside the 

fuel tank could result in a fuel tank 

explosion. 

To correct the unsafe condition, this 

directive mandates the installation of conduit 

and the addition of spacers to protect fuel 

tank wiring. 

Actions and Compliance 

(f) Unless already done, do the following 

actions. 

(1) Within 4,500 flight hours after the 

effective date of this AD, modify the fuel 

system wiring along the fuselage and in the 

avionics compartment by installing 

protective conduit and spacers, in 

accordance with the Accomplishment 

Instructions of Bombardier Service Bulletin 

670BA–24–011, Revision C, dated November 

28, 2005. 

(2) Actions done before the effective date 

of this AD in accordance with Bombardier 

Service Bulletin 670BA–24–011, dated 

September 7, 2004; Revision A, dated 

December 14, 2004; or Revision B, dated 

February 28, 2005; are acceptable for 

compliance with the corresponding 

requirements of this AD. 

FAA AD Differences 

Note: This AD differs from the MCAI and/ 

or service information as follows: No 

differences. 

Other FAA AD Provisions 

(g) The following provisions also apply to 

this AD: 

(1) Alternative Methods of Compliance 

(AMOCs): The Manager, New York Aircraft 

Certification Office (ACO), FAA, has the 

authority to approve AMOCs for this AD, if 

requested using the procedures found in 14 

CFR 39.19. Send information to ATTN: Rocco 

Viselli, Aerospace Engineer, Airframe and 

Propulsion Branch, ANE–171, FAA, New 

York ACO, 1600 Stewart Avenue, Suite 410, 

Westbury, New York 11590; telephone (516) 

228–7331; fax (516) 794–5531. Before using 

any approved AMOC on any airplane to 

which the AMOC applies, notify your 

appropriate principal inspector (PI) in the 

FAA Flight Standards District Office (FSDO), 

or lacking a PI, your local FSDO. 

(2) Airworthy Product: For any 

requirement in this AD to obtain corrective 

actions from a manufacturer or other source, 

use these actions if they are FAA-approved. 

Corrective actions are considered FAAapproved if they are approved by the State 

of Design Authority (or their delegated 

agent). You are required to assure the product 

is airworthy before it is returned to service. 

(3) Reporting Requirements: For any 

reporting requirement in this AD, under the 

provisions of the Paperwork Reduction Act, 

the Office of Management and Budget (OMB) 

has approved the information collection 

requirements and has assigned OMB Control 

Number 2120–0056. 

Related Information 

(h) Refer to MCAI Canadian Airworthiness 

Directive CF–2008–25, dated July 3, 2008, 

and Bombardier Service Bulletin 670BA–24– 

011, Revision C, dated November 28, 2005, 

for related information. 

Issued in Renton, Washington, on 

September 12, 2008. 

Michael Kaszycki, 

Acting Manager, Transport Airplane 

Directorate, Aircraft Certification Service. 

[FR Doc. E8–22218 Filed 9–22–08; 8:45 am] 

BILLING CODE 4910–13–P 

DEPARTMENT OF TRANSPORTATION 

Federal Aviation Administration 

14 CFR Part 39 

[Docket No. FAA–2008–0981; Directorate 

Identifier 2008–NM–073–AD] 

RIN 2120–AA64 

Airworthiness Directives; Boeing 

Model 747 Airplanes 

AGENCY: Federal Aviation 

Administration (FAA), Department of 

Transportation (DOT). 

ACTION: Notice of proposed rulemaking 

(NPRM). 

SUMMARY: The FAA proposes to 

supersede an existing airworthiness 

directive (AD) that applies to certain 

Boeing Model 747 airplanes. The 

existing AD currently requires repetitive 

inspections of the body station (BS) 

2598 bulkhead, and corrective actions if 

necessary. The existing AD also 

currently requires a terminating 

modification for the repetitive 

inspections and a post-modification 

inspection of the modified area. This 

proposed AD would continue requiring 

those actions with revised service 

information. For certain airplanes, this 

proposed AD would require new 

repetitive inspections, an interim 

modification, and post-interim 

modification inspections. For certain 

airplanes, this proposed AD also would 

require replacing any previously 

repaired aft inner chord and reinstalling 

the terminating modification. This 

proposed AD results from reports of 

cracked aft inner chords on airplanes 

after certain requirements of the existing 

AD were done. We are proposing this 

AD to prevent fatigue cracking of the BS 

2598 bulkhead structure, which could 

result in inability of the structure to 

carry horizontal stabilizer flight loads, 

and loss of controllability of the 

airplane. 

DATES: We must receive comments on 

this proposed AD by November 7, 2008. 

ADDRESSES: You may send comments by 

any of the following methods: 

• Federal eRulemaking Portal: Go to 

http://www.regulations.gov. Follow the 

instructions for submitting comments. 

• Fax: 202–493–2251. 

• Mail: U.S. Department of 

Transportation, Docket Operations, M– 

30, West Building Ground Floor, Room 

W12–140, 1200 New Jersey Avenue, SE., 

Washington, DC 20590. 

• Hand Delivery: U.S. Department of 

Transportation, Docket Operations, M– 

30, West Building Ground Floor, Room 

W12–140, 1200 New Jersey Avenue, SE., 

Washington, DC 20590, between 9 a.m. 

and 5 p.m., Monday through Friday, 

except Federal holidays. 

For service information identified in 

this AD, contact Boeing Commercial 

Airplanes, P.O. Box 3707, Seattle, 

Washington 98124–2207. 

Examining the AD Docket 

You may examine the AD docket on 

the Internet at http:// 

www.regulations.gov; or in person at the 

Docket Management Facility between 9 

a.m. and 5 p.m., Monday through 

Friday, except Federal holidays. The AD 

docket contains this proposed AD, the 

regulatory evaluation, any comments 

received, and other information. The 

street address for the Docket Office 

(telephone 800–647–5527) is in the 

ADDRESSES section. Comments will be 

available in the AD docket shortly after 

receipt. 

FOR FURTHER INFORMATION CONTACT: Ivan 

Li, Aerospace Engineer, Airframe 

Branch, ANM–120S, FAA, Seattle 

Aircraft Certification Office, 1601 Lind 

Avenue, SW., Renton, Washington 

98057–3356; telephone (425) 917–6437; 

fax (425) 917–6590. 

SUPPLEMENTARY INFORMATION: 

Comments Invited 

We invite you to send any written 

relevant data, views, or arguments about 

this proposed AD. Send your comments 

to an address listed under the 

ADDRESSES section. Include ‘‘Docket No. 

FAA–2008–0981; Directorate Identifier 

2008–NM–073–AD’’ at the beginning of 

your comments. We specifically invite 

comments on the overall regulatory, 

economic, environmental, and energy 

aspects of this proposed AD. We will 

consider all comments received by the 

closing date and may amend this 


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proposed AD because of those 

comments. 

We will post all comments we 

receive, without change, to http:// 

www.regulations.gov, including any 

personal information you provide. We 

will also post a report summarizing each 

substantive verbal contact we receive 

about this proposed AD. 

Discussion 

On February 22, 2006, we issued AD 

2006–05–06, amendment 39–14503 (71 

FR 12125, March 9, 2006), for certain 

Boeing Model 747 airplanes. That AD 

requires repetitive inspections of the 

body station (BS) 2598 bulkhead, and 

corrective action if necessary. That AD 

also requires modification of the 

bulkhead, including a one-time 

inspection and corrective action if 

necessary, which terminates certain 

repetitive inspections. In addition, that 

AD also requires a post-modification 

inspection of the modified area. That 

AD resulted from reports of fatigue 

cracking on BS 2598 bulkhead. We 

issued that AD to prevent fatigue 

cracking of the BS 2598 bulkhead 

structure, which could result in 

inability of the structure to carry 

horizontal stabilizer flight loads, and 

loss of controllability of the airplane. 

Actions Since Existing AD Was Issued 

Since we issued AD 2006–05–06, we 

have received a report of a cracked aft 

inner chord that was completely severed 

and a 0.5-inch crack in the adjacent 

frame support on an in-service airplane. 

These cracks have been attributed to 

fatigue. The airplane had accumulated 

9,988 total flight cycles and 68,081 total 

flight hours. A surface high frequency 

eddy current (HFEC) inspection had 

been done on the aft inner chord as 

required by AD 2006–05–06. In 

addition, we have received reports of 

cracked aft inner chords that had been 

previously repaired and not replaced 

before the bulkhead was modified in 

accordance with AD 2006–05–06. 

Repaired chords can have an active 

crack tip that may continue to 

propagate, even if the area has been 

reinforced. 

Therefore, we have determined that in 

addition to the repetitive surface HFEC 

inspections required by AD 2006–05– 

06, repetitive open hole surface HFEC 

inspections are necessary to detect 

cracks that are beneath the surface of the 

aft inner chords. We also have 

determined that the terminating 

modification, if installed with a repaired 

aft inner chord in place as required by 

AD 2006–05–06, does not adequately 

address the identified unsafe condition, 

and that further rulemaking is 

necessary. 

Relevant Service Information 

We have reviewed Revision 4 of 

Boeing Alert Service Bulletin 747– 

53A2427, dated March 6, 2008 (AD 

2006–05–06 refers to Boeing Alert 

Service Bulletin 747–53A2427, Revision 

2, dated October 5, 2000; or Revision 3, 

dated September 27, 2001; as 

appropriate sources of service 

information for accomplishing certain 

requirements). The repetitive surface 

HFEC inspections described in Revision 

4 are identical to those in earlier 

revisions of the service bulletin. 

Revision 4 adds new repetitive open 

hole HFEC inspections to detect cracks 

in the bulkhead splice fitting, frame 

support fitting, and forward and aft 

inner chords on the left and right side 

of the BS 2598 bulkhead, and repair if 

necessary. Revision 4 also adds a new 

interim modification for the aft inner 

chords, which defers the repetitive 

surface and open hole HFEC 

inspections. The compliance time for 

accomplishing the initial open hole 

inspection is before 6,000 or 16,000 total 

flight cycles (depending on the airplane 

configuration), or within 1,500 flight 

cycles after the date on Revision 4 of the 

service bulletin, whichever occurs later. 

The compliance time for accomplishing 

repetitive surface and open hole HFEC 

inspections is within 1,500 flight cycles 

after the last surface HFEC inspection of 

the forward side of the bulkhead or 

within 6,000 flight cycles after 

installation of the structural repair 

manual repair or interim modification, 

depending on the airplane 

configuration. 

We also have reviewed Revision 1 of 

Boeing Service Bulletin 747–53–2473, 

dated February 20, 2007 (AD 2006–05– 

06 refers to Boeing Service Bulletin 

747–53–2473, dated March 24, 2005; as 

an appropriate source of service 

information for accomplishing the 

terminating modification). Revision 1 

removes the option to re-install an aft 

inner chord that has been repaired 

before accomplishing the terminating 

modification. The modification and 

related investigative and corrective 

actions are essentially identical to those 

specified in Boeing Service Bulletin 

747–53–2473, dated March 24, 2005. 

Accomplishing the actions specified 

in the service information is intended to 

adequately address the unsafe 

condition. 

FAA’s Determination and Requirements 

of the Proposed AD 

We have evaluated all pertinent 

information and identified an unsafe 

condition that is likely to develop on 

other airplanes of the same type design. 

For this reason, we are proposing this 

AD, which would supersede AD 2006– 

05–06 and would retain the 

requirements of the existing AD. This 

proposed AD would also require 

accomplishing the actions specified in 

service information described 

previously, except as discussed under 

‘‘Differences Between the Proposed AD 

and Service Information.’’ 

Differences Between the Proposed AD 

and Service Information 

The service information described 

previously specifies to contact the 

manufacturer for instructions on how to 

repair certain conditions, but this 

proposed AD would require repairing 

those conditions in one of the following 

ways: 

• Using a method that we approve; or 

• Using data that meet the 

certification basis of the airplane, and 

that have been approved by an 

Authorized Representative for the 

Boeing Commercial Airplanes 

Delegation Option Authorization 

Organization whom we have authorized 

to make those findings. 

For certain airplanes, Boeing Service 

Bulletin 747–53–2473, Revision 1, does 

not specify a compliance time for 

replacing the previously repaired aft 

inner chord and reinstalling the 

terminating modification. In developing 

an appropriate compliance time for 

these proposed actions, we considered 

the degree of urgency associated with 

the subject unsafe condition, the 

manufacturer’s recommendation for an 

appropriate compliance time, and the 

average utilization of the affected fleet. 

In light of these factors, we find that a 

compliance time of within 3,000 flight 

cycles after doing the modification 

required by paragraph (l) of this AD, or 

within 1,500 flight cycles after the 

effective date of this AD, whichever 

occurs later, represents an appropriate 

interval of time for affected airplanes to 

continue to operate without 

compromising safety. This difference 

has been coordinated with Boeing. 

Explanation of Change Made to 

Requirements of AD 2006–05–06 

Retained in This AD 

We have simplified paragraphs (g), (i), 

and (k) of this AD by referring to the 

‘‘Alternative Methods of Compliance 

(AMOCs)’’ paragraph of this AD for 

repair methods. 

Costs of Compliance 

There are about 998 airplanes of the 

affected design in the worldwide fleet. 

The following table provides the 


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estimated costs for U.S. operators to 

comply with this proposed AD. 

ESTIMATED COSTS

Action Work hours 

Average 

labor rate 

per hour 

Parts Cost per airplane 

Number of 

U.S.- 

registered 

airplanes 

Fleet cost 

Surface HFEC inspections 

and open hole HFEC inspections.

2 $80 None ........... $160, per inspection cycle 162 $25,920, per inspection 

cycle. 

Detailed inspections .......... 2 80 None ........... $160, per inspection cycle 162 $25,920, per inspection 

cycle. 

Interim modification ........... 4 80 $4,000 ......... $4,320 .............................. 162 $699,840. 

Replacement of Previously 

Repaired Aft Inner 

Chords.

2 80 None ........... $160 ................................. 162 $25,920. 

Terminating modification ... 126 80 $33,716 ....... $43,796 ............................ 162 $7,094,952. 

Post-terminating modification inspection.4 80 None ........... $320 ................................. 162 $51,840. 

Authority for This Rulemaking 

Title 49 of the United States Code 

specifies the FAA’s authority to issue 

rules on aviation safety. Subtitle I, 

Section 106, describes the authority of 

the FAA Administrator. Subtitle VII, 

Aviation Programs, describes in more 

detail the scope of the Agency’s 

authority. 

We are issuing this rulemaking under 

the authority described in Subtitle VII, 

Part A, Subpart III, Section 44701, 

‘‘General requirements.’’ Under that 

section, Congress charges the FAA with 

promoting safe flight of civil aircraft in 

air commerce by prescribing regulations 

for practices, methods, and procedures 

the Administrator finds necessary for 

safety in air commerce. This regulation 

is within the scope of that authority 

because it addresses an unsafe condition 

that is likely to exist or develop on 

products identified in this rulemaking 

action. 

Regulatory Findings 

We have determined that this 

proposed AD would not have federalism 

implications under Executive Order 

13132. This proposed AD would not 

have a substantial direct effect 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. 

For the reasons discussed above, I 

certify that the 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. 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. 

We prepared a regulatory evaluation 

of the estimated costs to comply with 

this proposed AD and placed it in the 

AD docket. See the ADDRESSES section 

for a location to examine the regulatory 

evaluation. 

List of Subjects in 14 CFR Part 39 

Air transportation, Aircraft, Aviation 

safety, Safety. 

The Proposed Amendment 

Accordingly, under the authority 

delegated to me by the Administrator, 

the FAA proposes to amend 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. 

§ 39.13 [Amended] 

2. The Federal Aviation 

Administration (FAA) amends § 39.13 

by removing amendment 39–14503 (71 

FR 12125, March 9, 2006) and adding 

the following new airworthiness 

directive (AD): 

Boeing: Docket No. FAA–2008–0981; 

Directorate Identifier 2008–NM–073–AD. 

Comments Due Date 

(a) The FAA must receive comments on 

this AD action by November 7, 2008. 

Affected ADs 

(b) This AD supersedes AD 2006–05–06. 

Applicability 

(c) This AD applies to Boeing Model 747– 

100, 747–100B, 747–100B SUD, 747–200B, 

747–200C, 747–200F, 747–300, 747–400, 

747–400D, 747–400F, 747SR, and 747SP 

series airplanes, certificated in any category, 

line numbers 1 through 1307 inclusive. 

Unsafe Condition 

(d) This AD results from reports of cracked 

aft inner chords on airplanes after certain 

requirements of the existing AD were done. 

We are issuing this AD to prevent fatigue 

cracking of the body station (BS) 2598 

bulkhead structure, which could result in 

inability of the structure to carry horizontal 

stabilizer flight loads, and loss of 

controllability of the airplane. 

Compliance 

(e) You are responsible for having the 

actions required by this AD performed within 

the compliance times specified, unless the 

actions have already been done. 

Requirements of AD 2006–05–06 

Repetitive High Frequency Eddy Current 

(HFEC) Inspections of the Bulkhead Frame 

Supports 

(f) Before the accumulation of 10,000 total 

flight cycles, or within 1,000 flight cycles 

after August 16, 2001 (the effective date of 

AD 2001–14–07), whichever occurs later: Do 

an open-hole HFEC inspection to find 

cracking of the bulkhead frame support 

under the hinge support fittings of the 

horizontal stabilizer on the left and right 

sides at BS 2598, in accordance with Figure 

2 of the Accomplishment Instructions of 

Boeing Service Bulletin 747–53A2449, 

Revision 1, dated May 24, 2001; or Revision 

2, dated March 14, 2002. Repeat the 

inspection after that at intervals not to exceed 

3,000 flight cycles. Inspections accomplished 

before August 16, 2001, per Boeing Alert 

Service Bulletin 747–53A2449, dated June 8, 

2000, are considered acceptable for 

compliance with the applicable inspection 

specified in this paragraph. 

Repair of Any Cracked Bulkhead Frame 

Support 

(g) If any cracking is found during any 

inspection required by paragraph (f) of this 

AD, before further flight, repair using a 

method approved in accordance with the 


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procedures specified in paragraph (w) of this 

AD. 

Repetitive Inspections of Inner Chords, 

Frame Support, and Splice Fitting 

(h) Except as provided by paragraph (n) of 

this AD: Do a surface HFEC inspection of the 

forward and aft inner chords, the frame 

support, and the splice fitting of the forward 

inner chord of the upper corners of the 

station 2598 bulkhead to find cracking, in 

accordance with the Accomplishment 

Instructions of Boeing Alert Service Bulletin 

747–53A2427, Revision 2, dated October 5, 

2000; or Revision 3, dated September 27, 

2001; at the latest of the times specified in 

paragraphs (h)(1) and (h)(2) of this AD, as 

applicable. Repeat the inspection after that at 

intervals not to exceed 1,500 flight cycles. 

(1) For airplanes having line numbers 1 

through 1241 inclusive: 

(i) Before the accumulation of 6,000 total 

flight cycles. 

(ii) Within 500 flight cycles after August 

28, 2001 (the effective date of AD 2001–15– 

03). 

(iii) For airplanes inspected before August 

28, 2001, in accordance with Boeing Alert 

Service Bulletin 747–53A2427, dated 

December 17, 1998 (including inspections of 

the splice fitting), or Revision 1, dated 

October 28, 1999: Within 1,500 flight cycles 

after accomplishment of the last inspection 

done in accordance with the original service 

bulletin or Revision 1, as applicable. 

(2) For airplanes having line numbers 1242 

through 1307 inclusive: 

(i) Before the accumulation of 16,000 total 

flight cycles. 

(ii) Within 500 flight cycles after August 

28, 2001. 

(iii) For airplanes inspected before August 

28, 2001, in accordance with Boeing Alert 

Service Bulletin 747–53A2427, dated 

December 17, 1998 (including inspections of 

the splice fitting), or Revision 1, dated 

October 28, 1999: Within 1,500 flight cycles 

after accomplishment of the last inspection 

done in accordance with the original service 

bulletin or Revision 1, as applicable. 

Repair of Any Cracked Inner Chord, Frame 

Support, or Splice Fitting 

(i) If any cracking is found during the 

inspections required by paragraph (h) of this 

AD, before further flight, repair in accordance 

with the Accomplishment Instructions of 

Boeing Alert Service Bulletin 747–53A2427, 

Revision 2, dated October 5, 2000; or 

Revision 3, dated September 27, 2001; except 

as provided by paragraph (n) of this AD, and 

except where the alert service bulletin 

specifies that the manufacturer may be 

contacted for disposition of certain repair 

conditions, before further flight, repair using 

a method approved in accordance with the 

procedures specified in paragraph (w) of this 

AD. 

Repetitive Detailed Inspections of BS 2598 

Bulkhead 

(j) Before the accumulation of 10,000 total 

flight cycles, or within 1,000 flight cycles 

after October 27, 2003 (the effective date of 

AD 2003–19–08), whichever is later: Do a 

detailed inspection of the BS 2598 bulkhead 

for discrepancies (cracking, elongated 

fastener holes) of the areas specified in 

paragraphs (j)(1) and (j)(2) of this AD, in 

accordance with the Accomplishment 

Instructions of Boeing Alert Service Bulletin 

747–53A2467, dated July 26, 2001; or 

Revision 1, dated April 28, 2005. Repeat the 

inspections after that at intervals not to 

exceed 3,000 flight cycles. 

(1) The lower aft inner chords. 

(2) The upper aft outer chords, and the 

diagonal brace attachment fittings, flanges, 

and rods. 

Note 1: For the purposes of this AD, a 

detailed inspection is ‘‘an intensive 

examination of a specific item, installation, 

or assembly to detect damage, failure, or 

irregularity. Available lighting is normally 

supplemented with a direct source of good 

lighting at an intensity deemed appropriate. 

Inspection aids such as mirrors, magnifying 

lenses, etc. may be necessary. Surface 

cleaning and elaborate procedures may be 

required.’’ 

Repair of Any Cracked BS 2598 Bulkhead 

(k) If any discrepancy is found during any 

inspection required by paragraph (j) of this 

AD: Before further flight, repair in 

accordance with the Accomplishment 

Instructions of Boeing Alert Service Bulletin 

747–53A2467, dated July 26, 2001; or 

Revision 1, dated April 28, 2005. If the 

service bulletin specifies to contact Boeing 

for appropriate action: Before further flight, 

repair using a method approved in 

accordance with the procedures specified in 

paragraph (w) of this AD. 

Terminating Modification 

(l) Except as provided by paragraphs (p) 

and (q) of this AD: Before the accumulation 

of 20,000 total flight cycles, or within 48 

months after April 13, 2006 (the effective 

date of AD 2006–05–06), whichever occurs 

later, modify the bulkhead by doing all 

applicable actions including surface and 

open-hole HFEC inspections for cracking of 

the upper forward inner chords, aft inner 

chords, upper splice fittings, and frame 

support fittings, as specified in the 

Accomplishment Instructions of Boeing 

Service Bulletin 747–53–2473, dated March 

24, 2005. Repair any cracks before further 

flight in accordance with the service bulletin. 

Where the service bulletin specifies that the 

manufacturer may be contacted for 

disposition of certain repair conditions: 

Before further flight, repair the cracks using 

a method approved in accordance with the 

procedures specified in paragraph (w) of this 

AD. Accomplishment of the modification 

terminates the requirements of paragraph (f), 

(h), and (j)(1) of this AD. 

Post-Modification Inspection and Repair 

(m) Within 20,000 flight cycles after the 

modification required by paragraph (l) of this 

AD, inspect the BS 2598 bulkhead for cracks, 

and repair any cracks before further flight, in 

accordance with a method approved by the 

Manager, Seattle Aircraft Certification Office 

(ACO). 

New Requirements of This AD 

New Revision of Service Bulletin 

(n) As of the effective date of this AD, use 

only the Accomplishment Instructions of 

Boeing Alert Service Bulletin 747–53A2427, 

Revision 4, dated March 6, 2008, to do the 

repetitive surface HFEC inspections required 

by paragraph (h) of this AD and the repair 

required by paragraph (i) of this AD. 

Terminating Repair for Repetitive Surface 

HFEC Inspections 

(o) As of the effective date of this AD, 

accomplishment of the aft inner chord repair 

required by paragraph (i) of this AD in 

accordance with the applicable structural 

repair manual (SRM) specified in the 

Accomplishment Instructions of Boeing Alert 

Service Bulletin 747–53A2427, Revision 4, 

dated March 6, 2008, ends the repetitive 

surface HFEC inspections required by 

paragraph (h) of this AD for that side of the 

bulkhead only. 

Replacement of Previously Repaired Aft 

Inner Chord and Reinstallation of 

Terminating Modification 

(p) For airplanes on which the terminating 

modification required by paragraph (l) of this 

AD has been done before the effective date 

of this AD, and on which any previously 

repaired aft inner chord was not replaced 

during that terminating modification: Within 

3,000 flight cycles after doing the 

modification, or within 1,500 flight cycles 

after the effective date of this AD, whichever 

occurs later, replace any previously repaired 

aft inner chord with a new aft inner chord 

and reinstall the terminating modification 

using a method approved in accordance with 

the procedures specified in paragraph (w) of 

this AD. Accomplishment of the replacement 

and reinstallation of the terminating 

modification terminates the requirements of 

paragraphs (l) and (m) of this AD and 

repetitive inspections required by this AD, 

except for the inspections specified in 

paragraph (r) of this AD. 

Revised Terminating Modification 

(q) For airplanes on which the terminating 

modification required by paragraph (l) of this 

AD has not been done as of the effective date 

of this AD: Before the accumulation of 20,000 

total flight cycles, or within 18 months after 

the effective date of this AD, whichever 

occurs later, modify and do applicable 

relative investigative and corrective actions 

by doing all the applicable actions specified 

in the Accomplishment Instructions of 

Boeing Service Bulletin 747–53–2473, 

Revision 1, dated February 20, 2007; except 

where the service bulletin specifies that the 

manufacturer may be contacted for 

disposition of certain repair conditions, 

before further flight, repair the cracks using 

a method approved in accordance with the 

procedures specified in paragraph (w) of this 

AD. The applicable related investigative and 

corrective actions must be done before 

further flight. Accomplishment of the 

replacement and reinstallation of the 

terminating modification terminates the 

requirements of paragraphs (l) and (m) of this 

AD and repetitive inspections required by 


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this AD, except for the inspections specified 

in paragraph (r) of this AD. 

Post-Modification Inspection and Repair 

(r) Within 20,000 flight cycles after the 

modification required by paragraph (p) or (q) 

of this AD, as applicable, inspect the BS 2598 

bulkhead for cracks, and repair any crack 

before further flight, in accordance with a 

method approved by the Manager, Seattle 

ACO. 

Open Hole HFEC Inspection(s) and 

Terminating Repair 

(s) For airplanes on which the terminating 

modification required by paragraph (l) or (q) 

of this AD has not been done: Do an initial 

open hole HFEC inspection to detect cracks 

in the bulkhead splice fitting, frame support 

fitting, and forward and aft inner chords on 

the left and right sides of the BS 2598 

bulkhead, in accordance with the 

Accomplishment Instructions of Boeing Alert 

Service Bulletin 747–53A2427, Revision 4, 

dated March 6, 2008. Do the initial 

inspection at the applicable time specified in 

Table 1 or 3 of paragraph 1.E., ‘‘Compliance,’’ 

of the service bulletin; except, where the 

service bulletin specifies a compliance time 

after the date on the service bulletin, this AD 

requires compliance within the specified 

compliance time after the effective date of 

this AD. 

(1) If no crack is detected, repeat the open 

hole HFEC inspection thereafter at intervals 

not to exceed 1,500 flight cycles. 

(2) If any crack is detected, before further 

flight, repair it in accordance with the service 

bulletin; except, where the service bulletin 

specifies to contact Boeing for appropriate 

action, before further flight, repair the crack 

using a method approved in accordance with 

the procedures specified in paragraph (w) of 

this AD. Accomplishment of the aft inner 

chord repair in accordance with the 

applicable SRM specified in the 

Accomplishment Instructions of the service 

bulletin ends the repetitive open hole HFEC 

inspections required by paragraphs (h) and 

(s)(1) of this AD for that side of the bulkhead 

only. 

Interim Modification 

(t) For Group 1 airplanes, as identified in 

Boeing Alert Service Bulletin 747–53A2427, 

Revision 4, dated March 6, 2008, on which 

the terminating modification required by 

paragraph (l) or (q) of this AD has not been 

done: Before the accumulation of 12,000 total 

flight cycles, or within 1,500 flight cycles 

after the effective date of this AD, whichever 

occurs later, install the interim modification 

for the aft inner chords, in accordance with 

the Accomplishment Instructions of the 

service bulletin. Accomplishment of the 

interim modification ends the repetitive open 

hole and surface HFEC inspections required 

by paragraphs (h) and (s)(1) of this AD. 

Post-Interim Modification/Repair Repetitive 

Surface and Open Hole HFEC Inspections 

(u) For airplanes on which the interim 

modification required by paragraph (t) of this 

AD has been done or the repair of any 

cracked aft inner chord has been done in 

accordance with the SRM specified in the 

Accomplishment Instructions of Boeing Alert 

Service Bulletin 747–53A2427, Revision 4, 

dated March 6, 2008, as required by 

paragraph (i) or (s)(2) of this AD; and on 

which the terminating modification required 

by paragraph (l) or (q) of this AD has not been 

done: At the applicable times specified in 

Table 1, 2, or 3 of paragraph 1.E., 

‘‘Compliance,’’ of the service bulletin, do a 

surface HFEC inspection to detect cracks on 

the forward side (unmodified area) of the 

bulkhead and open hole and surface HFEC 

inspections to detect cracks in the modified 

or repaired area, in accordance with the 

Accomplishment Instructions of Boeing Alert 

Service Bulletin 747–53A2427, Revision 4, 

dated March 6, 2008. Repeat the open hole 

and surface HFEC inspections thereafter at 

intervals not to exceed 1,500 flight cycles, 

until the modification required by paragraph 

(q) of this AD is done, as applicable; except, 

for airplanes on which the repair of any 

cracked aft inner chord has been done on 

only one side of the bulkhead in accordance 

with the applicable SRM as required by 

paragraph (i) or (s)(2) of this AD, the 

repetitive open hole and surface HFEC 

inspections required by paragraph (h) and 

(s)(1) of this AD must continue to be done for 

the other side of the bulkhead. 

Repair of Any Cracked Inner Chord, Splice 

Fitting, or Frame Support Fitting 

(v) If any crack is detected during any open 

hole or surface HFEC inspection required by 

paragraph (u) of this AD, before further flight, 

repair any cracked inner chord, splice fitting, 

or frame support fitting, in accordance with 

the Accomplishment Instructions of Boeing 

Alert Service Bulletin 747–53A2427, 

Revision 4, dated March 6, 2008; except, 

where the service bulletin specifies to contact 

Boeing for appropriate action, before further 

flight, repair the crack using a method 

approved in accordance with the procedures 

specified in paragraph (w) of this AD. 

Alternative Methods of Compliance 

(AMOCs) 

(w)(1) The Manager, Seattle ACO, FAA, 

ATTN: Ivan Li, Aerospace Engineer, Airframe 

Branch, ANM–120S, FAA, Seattle ACO, 1601 

Lind Avenue, SW., Renton, Washington 

98057–3356; telephone (425) 917–6437; fax 

(425) 917–6590; has the authority to approve 

AMOCs for this AD, if requested using the 

procedures found in 14 CFR 39.19. 

(2) To request a different method of 

compliance or a different compliance time 

for this AD, follow the procedures in 14 CFR 

39.19. Before using any approved AMOC on 

any airplane to which the AMOC applies, 

notify your appropriate principal inspector 

(PI) in the FAA Flight Standards District 

Office (FSDO), or lacking a PI, your local 

FSDO. 

(3) An AMOC that provides an acceptable 

level of safety may be used for any repair 

required by this AD, if it is approved by an 

Authorized Representative for the Boeing 

Commercial Airplanes Delegation Option 

Authorization Organization who has been 

authorized by the Manager, Seattle ACO, to 

make those findings. For a repair method to 

be approved, the repair must meet the 

certification basis of the airplane, and the 

approval must specifically refer to this AD. 

(4) AMOCs approved previously in 

accordance with AD 2006–05–06 are 

approved as AMOCs for the corresponding 

provisions of this AD. 

Issued in Renton, Washington, on 

September 11, 2008. 

Michael Kaszycki, 

Acting Manager, Transport Airplane 

Directorate, Aircraft Certification Service. 

[FR Doc. E8–22215 Filed 9–22–08; 8:45 am] 

BILLING CODE 4910–13–P 

DEPARTMENT OF TRANSPORTATION 

Federal Aviation Administration 

14 CFR Part 39 

[Docket No. FAA–2008–1006; Directorate 

Identifier 2008–NM–110–AD] 

RIN 2120–AA64 

Airworthiness Directives; Boeing 

Model 747–100, 747–100B, 747–200B, 

747–200C, 747–200F, 747–300, 747SR, 

and 747SP Series Airplanes 

AGENCY: Federal Aviation 

Administration (FAA), Department of 

Transportation (DOT). 

ACTION: Notice of proposed rulemaking 

(NPRM). 

SUMMARY: The FAA proposes to 

supersede an existing airworthiness 

directive (AD) that applies to certain 

Boeing Model 747–100, 747–100B, 747– 

200B, 747–200C, 747–200F, 747–300, 

747SR, and 747SP series airplanes. The 

existing AD currently requires an 

inspection to determine if acceptable 

external skin doublers are installed at 

the stringer 6 (S–6) lap splices, between 

station (STA) 340 and STA 400. For 

airplanes without the acceptable 

external skin doublers, the existing AD 

requires repetitive related investigative 

actions and corrective actions if 

necessary. The existing AD also 

provides an optional terminating 

modification for the repetitive related 

investigative actions. This proposed AD 

would mandate the optional terminating 

modification. This proposed AD results 

from a report of cracked fastener holes 

at the right S–6 lap splice between STA 

340 and STA 380. We are proposing this 

AD to prevent cracking in the fuselage 

skin, which could result in rapid 

decompression and loss of structural 

integrity of the airplane. 

DATES: We must receive comments on 

this proposed AD by November 7, 2008. 

ADDRESSES: You may send comments by 

any of the following methods: 

• Federal eRulemaking Portal: Go to 

http://www.regulations.gov. Follow the 

instructions for submitting comments. 


jlentini on PROD1PC65 with PROPOSALS