54206 Federal Register / Vol. 69, No. 173 / Wednesday, September 8, 2004 / Rules and Regulations 

DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration 

14 CFR Part 39 

[Docket No. 2001–NM–246–AD; Amendment 

39–13784; AD 2004–18–06] 

RIN 2120–AA64 

Airworthiness Directives; Boeing 

Model 737–200, –200C, –300, –400, and 

–500 Series Airplanes

AGENCY: Federal Aviation 

Administration, DOT.

ACTION: Final rule.

SUMMARY: This amendment adopts a 

new airworthiness directive (AD), 

applicable to certain Boeing Model 737–

200, –200C, –300, –400, and –500 series 

airplanes, that requires repetitive 

inspections to find fatigue cracking of 

certain upper and lower skin panels of 

the fuselage, and follow-on and 

corrective actions, if necessary. This 

amendment also includes terminating 

action for the repetitive inspections of 

certain modified or repaired areas only. 

This action is necessary to find and fix 

fatigue cracking of the skin panels, 

which could result in sudden fracture 

and failure of the skin panels of the 

fuselage, and consequent rapid 

decompression of the airplane. This 

action is intended to address the 

identified unsafe condition.

DATES: Effective October 13, 2004. 

The incorporation by reference of 

certain publications listed in the 

regulations is approved by the Director 

of the Federal Register as of October 13, 

2004.

ADDRESSES: The service information 

referenced in this AD may be obtained 

from Boeing Commercial Airplanes, 

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 National Archives 

and Records Administration (NARA). 

For information on the availability of 

this material at NARA, call (202) 741–

6030, or go to: http://www.archives.gov/

federal_register/

code_of_federal_regulations/

ibr_locations.html.

FOR FURTHER INFORMATION CONTACT:

Suzanne Lucier, Aerospace Engineer, 

Airframe Branch, ANM–120S, FAA, 

Seattle Aircraft Certification Office, 

1601 Lind Avenue, SW., Renton, 

Washington 98055–4056; telephone 

(425) 917–6438; fax (425) 917–6590.

SUPPLEMENTARY INFORMATION: A 

proposal to amend part 39 of the Federal 

Aviation Regulations (14 CFR part 39) to 

include an airworthiness directive (AD) 

that is applicable to certain Boeing 

Model 737–200, –200C, –300, –400, and 

–500 series airplanes was published in 

the Federal Register on June 18, 2003 

(68 FR 36515). That action proposed to 

require repetitive inspections to find 

fatigue cracking of certain upper and 

lower skin panels of the fuselage, and 

follow-on and corrective actions, if 

necessary. That action also includes 

terminating action for the repetitive 

inspections of certain modified or 

repaired areas only. 

Comments 

Interested persons have been afforded 

an opportunity to participate in the 

making of this amendment. Due 

consideration has been given to the 

comments received. 

Agreement With Proposed Rule 

One commenter generally agrees with 

the proposed rule. 

Request To Clarify Repetitive Eddy 

Current Inspections 

Several commenters request 

clarification of the repetitive eddy 

current inspections required by 

paragraph (a) of the proposed rule. The 

commenters note that the proposed rule 

differs from the service bulletin in that 

the proposed rule requires both external 

detailed and eddy current inspections 

every 4,500 flight cycles, while the 

service bulletin only specifies to repeat 

the detailed inspections. One 

commenter asks if the repetitive eddy 

current inspections are mandatory. 

Another commenter points out that no 

explanation is given in the preamble of 

the proposed rule in the ‘‘Differences’’

paragraph. Because no technical reason 

is given for this change, the commenter 

believes the proposed rule’s intent was 

not to include repetitive eddy current 

inspections that are beyond the scope of 

the service bulletin. 

Another commenter, the 

manufacturer, agrees with the proposed 

rule that the eddy current inspections 

should be repetitive. The commenter 

states that because of recent upper row 

cracks found on a Model 737 series 

airplane with disbonded waffle 

doublers, it seems prudent to use the 

more sensitive eddy current inspection 

at repetitive intervals of 4,500 flight 

cycles. The commenter notes that only 

external detailed inspections were 

originally used because it was assumed 

that the tear straps were bonded and 

functioning to slow down the cracks 

until they could easily be detected using 

visual methods. The commenter states 

that in the case of a disbonded panel, it 

is unclear if the chem-mill type crack 

would slow down as it approaches the 

tear straps. The commenter believes that 

if it is assumed that tear straps do not 

slow the growth of the cracks, then the 

repetitive external detailed inspections 

every 4,500 flight cycles would allow 

more than two inspection opportunities 

to pass as cracks detectable by eddy 

current inspections become critical. 

We agree with the request to clarify 

the repetitive eddy current inspections 

required by paragraph (a) of the final 

rule. Paragraph (a) of the proposed rule 

did specify repetitive external detailed 

and eddy current inspections but stated 

this as ‘‘repeat the inspections.’’

Because the service bulletin only 

specifies repetitive detailed inspections, 

we should have explained the difference 

in the ‘‘Differences’’ paragraph of the 

proposed rule for the reasons stated by 

the last commenter (i.e. because of the 

recent upper row cracks found on an 

airplane with disbonded waffle 

doublers). However the ‘‘Differences’’

paragraph of the proposed rule is not 

repeated in the final rule. We have 

clarified the repetitive eddy current 

inspections by revising paragraph (a) of 

the final rule to state, ‘‘Repeat the 

external detailed and eddy current 

inspections * * *.’’

Request To Revise Text To Describe the 

Area of Inspection 

One commenter requests to revise the 

text in paragraph (a) of the proposed 

rule from ‘‘crown area’’ to ‘‘crown area 

and other known areas of cracking.’’ The 

commenter states that the inspections in 

Part 1 and Figure 1 of Boeing Alert 

Service Bulletin 737–53A1210, Revision 

1, dated October 25, 2001 (referenced as 

the appropriate source of service 

information in the proposed rule), 

include areas of known cracking outside 

the crown. The commenter believes that 

since paragraph (a) of the proposed rule 

states to inspect only the ‘‘crown area,’’

then the areas of known cracking 

outside the crown as specified in the 

service bulletin may not get inspected. 

In addition, another commenter notes 

that it reported a crack at S12L on a 

Boeing Model 737–300 series airplane. 

The FAA agrees with the commenter 

that the text to describe the area of 

inspection should be revised. While the 

heading of Part 1 of the service bulletin 

(like the proposed rule) makes reference 

only to the crown area, Part 1 includes 

inspections outside that area, as stated 

by the commenter. We proposed to 

require all of the actions specified in 

Part 1 and Figure 1 of the service 

bulletin. For the reasons stated by that

Federal Register / Vol. 69, No. 173 / Wednesday, September 8, 2004 / Rules and Regulations 54207

commenter, we have clarified paragraph 

(a) of the final rule to state, ‘‘* * * 

crown area and other known areas of 

fuselage skin cracking, per Part 1 and 

Figure 1 * * *.’’ This clarification does 

not expand the inspection locations 

specified in Part 1 and Figure 1. 

Request To Reduce Inspection Area 

One commenter requests reducing the 

area of the eddy current inspection 

required by paragraph (a) of the 

proposed rule from body station (BS) 

360 to BS 1016 to the area BS 460 to BS 

787. The commenter contends that the 

cracking reported in the upper crown at 

locations ranging from BS 480 to BS 

777, per Boeing Service Bulletin 737–

53A1210, Revision 1, does not warrant 

accomplishing both a visual and an 

eddy current inspection of areas BS 360 

to BS 1016. The commenter 

recommends a visual inspection for 

areas BS 360 to BS 1016 and an eddy 

current inspection for areas BS 460 to 

BS 787.

We do not agree with the request to 

reduce the area of the eddy current 

inspection required by paragraph (a) of 

the final rule. Since the issuance of the 

service bulletin, we have received new 

reports of cracking. To address the 

identified unsafe condition, detailed 

and eddy current inspections are 

required by paragraph (a) of the final 

rule for areas BS 360 to BS 1016 

identified in the service bulletin. No 

change is made to the final rule in this 

regard. 

Request To Clarify Inspections of 

Chem-mill Areas 

Two commenters request clarification 

of inspections for chem-mill areas 

covered by FAA-approved or accepted 

repairs other than external repair 

doublers that extend a minimum of 

three rows of fasteners above and below 

the chem-mill steps. One commenter, 

the manufacturer, requests that an 

inspection be added to the proposed 

rule for areas that are covered by 

external repair doublers that do not 

extend a minimum of three rows of 

fasteners above and below the chemmill steps because paragraph (a) of the 

proposed rule does not address 

inspecting these areas. The commenter 

states that Boeing has developed a new 

internal inspection method for chemmill cracks under the external repair 

doublers, as specified in Boeing 737 

Non-Destructive Test (NDT) Manual, 

Part 6, Subject 53–30–20. The 

commenter contends that this 

inspection method can be used as a 

substitute for the external inspections 

with no change in the proposed 

compliance times. The commenter 

believes that chem-mill cracks under a 

repair doubler that do not extend 

beyond the chem-mill step are just as 

critical because three rows are required 

to carry failsafe loads. However, the 

commenter believes the cracks in this 

area are inspected less than cracks 

addressed by the proposed rule, and 

that it is likely repairs have been 

installed over undetected chem-mill 

cracks. The other commenter 

recommends that a general visual 

inspection of the repair for chem-milled 

areas covered by other FAA-approved or 

accepted repairs be added to the 

proposed rule, or that the areas be 

exempted from the inspections required 

by paragraphs (a) and (b) of the 

proposed rule. 

We agree that inspections of the 

chem-mill areas should be clarified. 

Inspections are not required in areas 

that are spanned by an FAA-approved 

repair that has a minimum of 3 rows of 

fasteners above and below the chemmilled step. If an external doubler 

covers the chem-milled step, but does 

not span it by a minimum of 3 rows of 

fasteners above and below, operators 

must request an alternative method of 

compliance (AMOC) as required by 

section 39.17 of the Federal Aviation 

Regulations (14 CFR 39.17). In lieu of 

requesting an AMOC, one method of 

compliance with the inspection 

requirement of paragraphs (a) and (b) of 

this final rule is to inspect all chemmilled steps covered by the repair using 

internal nondestructive test (NDT) 

methods in accordance with Boeing 737 

NDT Manual, Part 6, Subject 53–30–20. 

We have included new paragraph (i) of 

this final rule to provide inspection 

procedures, in lieu of requesting an 

AMOC, as one method of compliance 

with the requirements of paragraphs (a) 

and (b) of this final rule. 

Request To Clarify Inspection 

Requirements in the Area of an Internal 

Doubler at the Emergency Door 

Surround Structure 

One commenter requests that an 

inspection method be specified for the 

area of the internal doubler at the 

emergency exit surround structure as 

shown in Figure 5 of the service 

bulletin, or that the requirement to 

inspect this area be removed. The 

commenter notes that inspecting the 

area between BS 540 and BS 727 would 

require a different inspection procedure 

than the Boeing 737 NDT Manual, Part 

6, Subject 53–30–18 or 53–30–19 

procedures which are specified in 

Figure 5 of Boeing Alert Service Bulletin 

737–53A1210, Revision 1, dated 

October 25, 2001. 

We agree with the commenter that 

there should not be a requirement to 

inspect this area because the internal 

doubler that extends above S–10 

stabilizes the skin in this area and 

eliminates this area as a cracking 

concern. However, there is not a need to 

clarify this in the final rule because the 

service bulletin does not specify to 

inspect this area. This area is shown 

with a dotted line in Figure 5 of the 

service bulletin and is excluded from 

the inspections in Figure 5. Therefore, 

no change to the final rule is necessary. 

Request To Clarify Terminating Action 

for Repetitive Inspections 

Two commenters request that the 

terminating action for the repetitive 

inspections required by paragraph (a) of 

the proposed rule be clarified. One 

commenter states that the proposed rule 

requires to ‘‘Repeat the inspections at 

least every 4,500 flight cycles until 

paragraph (c) or (d)(1)(ii) of this AD has 

been done, as applicable.’’ The 

commenter notes that paragraph (c) and 

(d)(1)(ii) of the proposed rule do not 

cover the joint cutout modification per 

paragraph (g) of AD 2002–07–08, 

amendment 39–12702 (67 FR 17917). 

The commenter contends that the lap 

joint repair per paragraph (g) of AD 

2002–07–08 ends the repetitive 

inspections for those lap joints, and 

therefore, should be included as a 

terminating action in paragraph (a) of 

the proposed rule. The other commenter 

questions if the statement ‘‘Installation 

of the lap joint repair * * * is 

considered acceptable for compliance 

with * * *’’ in paragraph (d)(1) of the 

proposed AD ends the repetitive 

inspections per paragraph (a) of the 

proposed AD for those lap joints. 

We agree with the commenters that 

we should clarify the terminating 

actions for the repetitive actions for the 

reasons stated by the first commenter. 

The lap joint modification (repair) is an 

alternate method of compliance for the 

repetitive requirements of paragraph (a) 

of the final rule. There is language in 

paragraph (d)(1) of the AD that does 

specify, ‘‘Installation of the lap joint 

repair specified in paragraph (g) of AD 

2002–07–08, amendment 39–12702, is 

considered acceptable for compliance 

with the corresponding action specified 

in this paragraph for the lap joint areas 

only.’’ We have moved this language to 

paragraph (d)(1)(ii) of the final rule to 

clarify that modifications performed in 

accordance with paragraph (g) of AD 

2002–07–08 are considered a 

terminating modification for the chemmill step areas within the modified 

areas.

54208 Federal Register / Vol. 69, No. 173 / Wednesday, September 8, 2004 / Rules and Regulations 

Request To Add New Repair Option 

One commenter requests that a new 

repair option be added to paragraph (d) 

of the proposed rule. Paragraph (d) of 

the proposed rule provides two options 

for repair if cracking is found. The 

commenter points out that general skin 

repairs have been added to Boeing 737 

structural repair manuals, and that these 

repairs meet or exceed the requirements 

as stated in paragraph (d) of the 

proposed rule. The commenter suggests 

adding paragraph (d)(3) to the proposed 

rule stating, ‘‘For cracking in any area 

within the limitations of 737–100/200 

SRM 53–30–3 Figure 48 for –100’s and 

–200 aircraft, 737–300 SRM 53–00–01 

Figure 229 for –300 aircraft, 737–400 

SRM 53–00–01 Figure 231 for –400 

aircraft, and 737–500 SRM 53–00–01 

Figure 229 for –500 aircraft, cracks can 

be repaired per these SRM figures as 

applicable. Accomplishment of these 

repairs ends the repetitive inspections 

required by paragraph (b) of this AD for 

the repaired area only.’’ The commenter 

also suggests revising the first sentence 

of paragraph (d) of the proposed rule to 

state, ‘‘* * * specified in paragraphs 

(d)(1), (d)(2), and (d)(3) of this AD, as 

applicable * * *.’’ The commenter 

points out that these SRM repairs are 

being used extensively within the 

industry to repair skin damage, 

including chem-mill cracks. 

We agree with the commenter that the 

new repair option should be added and 

concur with its justification. 

Accordingly, we have added paragraph 

(e) to the final rule as follows: ‘‘For 

cracking in any area specified in 

paragraphs (d)(1) and (d)(2) of this AD 

within the limitations of Chapter 53, 

Subject 53–30–3, Figure 48 (for Model 

737–100 and –200 series airplanes), of 

the Boeing 737–100 and –200 Structural 

Repair Manual (SRM); Chapter 53, 

Subject 53–00–01, Figure 229 (for Model 

737–300 airplanes), of the Boeing 737–

300 SRM; Chapter 53, Subject 53–00–01, 

Figure 231 (for Model 737–400 series 

airplanes), of the Boeing 737–400 SRM; 

and Chapter 53, Subject 53–00–01, 

Figure 229 (for Model 737–500 series 

airplanes), of the Boeing 737–500 SRM; 

repair cracks per the applicable SRM. 

Accomplishment of the applicable 

repair terminates the repetitive 

inspections required by paragraphs (a) 

and (b) of this AD for the repaired area 

only.’’ We also revised paragraphs (a) 

and (b) of the final rule to include 

paragraph (e) of the final rule as an 

optional terminating action for the 

repaired area only. In addition, we 

revised paragraphs (d)(1) and (d)(2) of 

the final rule by adding paragraph (e) of 

the final rule as a repair option. 

Request To Revise Repair Instructions 

One commenter requests that the 

repair instructions in paragraph (d)(2) of 

the proposed rule be revised. The 

commenter notes that paragraph (d)(2) 

gives instructions to ‘‘* * * repair per 

Part 2 of the Work Instructions of the 

service bulletin * * *,’’ and the service 

bulletin specifies to ask Boeing for 

repair data. The commenter contends 

that an operator may interpret paragraph 

(d)(2) of the proposed rule as requiring 

them to contact Boeing for all repairs in 

the lower lobe and section 41. The 

commenter suggests revising paragraph 

(d)(2) of the proposed rule to state, ‘‘For 

cracking of the lower lobe area and 

Section 41, repair per paragraph (d)(3) 

of this AD before further flight * * *.’’

We disagree with the commenter to 

revise paragraph (d)(3) of the final rule 

per its suggested wording. As stated 

earlier, paragraph (d)(2) of the final rule 

has been revised by adding paragraph 

(e) of the final rule as an option to the 

repair of the cracking of the lower lobe 

and Section 41 done per Part 2 of the 

Work Instructions of the service 

bulletin. Operators should note that 

while the service bulletin does specify 

to contact Boeing for repair, paragraph 

(d) of the final rule requires operators to 

contact the FAA or a Designated 

Engineering Representative (DER) if the 

service bulletin specifies to contact 

Boeing for repair instructions. No 

change is made to the final rule in this 

regard.

Request To Add Inspection 

Requirement 

One commenter requests that the 

external subsurface inspection of the 

chem-mill steps in adjacent bays per 

step 2 of Figure 18 of the service 

bulletin be added to paragraph (e)(2) of 

the proposed rule. The commenter notes 

that paragraph (e)(2) of the proposed 

rule requires an ‘‘internal eddy current 

inspection of the skin, tear straps, and 

lap joint * * *’’ The commenter states 

that, while this agrees with the service 

bulletin, the service bulletin also 

specifies an external subsurface 

inspection of the chem-mill steps in 

adjacent bays. The commenter points 

out that when the time-limited repair 

required by paragraph (e) of the 

proposed rule is accomplished at remote 

sites, it may not be possible to do an 

NDT inspection of the adjacent chemmill steps. The commenter states that, 

often times in service, the bays adjacent 

to the cracked bay will also have cracks. 

The commenter also notes that 

inspection of the adjacent bays within 

4,000 flight cycles after doing the repair 

is recommended by the service bulletin 

as a precautionary measure. 

We agree with the commenter that the 

service bulletin also specifies external 

subsurface inspection of the chem-mill 

steps in adjacent bays. In our effort to 

describe the types of inspections 

referenced in Part 4 of the service 

bulletin, we inadvertently omitted the 

one mentioned by the commenter. We 

had no intention of deviating from the 

service bulletin. To clarify this intent, 

the final rule has been revised to track 

the precise wording of Part 4 of the 

service bulletin: ‘‘Do inspections of the 

repaired area * * *.’’

Request To Remove ‘‘Tear Straps’’

From Inspection Description 

One commenter requests that the 

words ‘‘tear straps’’ be removed from 

paragraph (e)(2) of the proposed rule. 

The commenter notes that the internal 

inspection shown in Figure 18 of the 

service bulletin looks for cracks in the 

skin under the tear strap and does not 

look for cracks in the tear straps. 

We agree with the commenter that the 

words ‘‘tear straps’’ be removed from 

paragraph (f)(2) of the final rule 

(specified as paragraph (e)(2) of the 

proposed rule). As stated previously, 

paragraph (f)(2) of the final rule 

(specified as paragraph (e)(2) of the 

proposed rule) has been changed to 

state, ‘‘Do the inspections of the 

repaired area * * *.’’

Request To Add Inspection for 

Disbonding To Terminate Repetitive 

Eddy Current Inspections 

One commenter requests that an 

inspection for disbonding be added that 

would terminate the repetitive eddy 

current inspections required by 

paragraph (a) of the proposed rule. The 

commenter recommends that the 

inspection for disbonding specified in 

Boeing Service Bulletin 737–53–1179, 

Revision 2, dated October 25, 2001, be 

added as a terminating action for the 

repetitive eddy current inspections 

required by paragraph (a) of the 

proposed rule, and then only repetitive 

detailed inspections would be needed to 

ensure safety. 

We agree that an inspection for 

disbonding should be added to 

terminate the repetitive eddy current 

inspections required by paragraph (a) of 

the final rule. The inspection for 

disbonding specified in Boeing Service 

Bulletin 737–53–1179, Revision 2, dated 

October 25, 2001, will verify the 

integrity of the doublers, and therefore, 

the repetitive eddy current inspections 

will no longer be required. The service 

bulletin is the source of service 

information for paragraphs (b) and (c) of

Federal Register / Vol. 69, No. 173 / Wednesday, September 8, 2004 / Rules and Regulations 54209

AD 2003–14–06, amendment 39–13225. 

That AD requires repetitive inspections 

for cracking of certain lap splices, and 

corrective action if necessary. We have 

added paragraph (g) to the final rule as 

follows: ‘‘Accomplishment of paragraph 

(b) or (c), as applicable, of AD 2003–14–

06, amendment 39–13225, terminates 

the repetitive eddy current inspections 

required by paragraph (a) of this AD; 

however the repetitive detailed 

inspections required by paragraph (a) of 

this AD are still required.’’

Request To Exclude Appendix A From 

Service Bulletin References 

Two commenters request that the 

phrase ‘‘including Appendix A’’ in 

paragraphs (a) through (e) of the 

proposed rule either be removed or 

changed to ‘‘excluding Appendix A.’’

One commenter notes that Appendix A 

of the service bulletin is an optional cost 

benefit analysis worksheet that is 

included in the service bulletin for the 

benefit of the operators if they elect to 

use it and that it has no effect on the 

repair, modification, or compliance 

instructions of the referenced service 

bulletin. The other commenter 

questions why Appendix A is 

mandatory and what operators should 

do with it if it is not excluded from the 

proposed rule. 

We agree that Appendix A should be 

excluded from the service bulletin 

references for the reasons stated by the 

first commenter. We removed the 

wording ‘‘including Appendix A’’ from 

paragraphs (a) through (d) of the final 

rule and paragraph (f) of the final rule 

(specified as paragraph (e) of the 

proposed rule). We also removed the 

wording ‘‘excluding Evaluation Form.’’

Explanation of Editorial Changes 

We have revised certain wording 

regarding the compliance times of the 

repetitive inspection requirements 

specified in paragraphs (a), (b), and 

(f)(1) (specified as paragraph (e)(1) of the 

proposed rule) of the final rule. Instead 

of specifying that the repetitive 

inspections be repeated ‘‘at least every,’’

as stated in paragraphs (a), (b), and (e)(1) 

of the proposed rule, this final rule 

specifies that the inspections be 

repeated ‘‘at intervals not to exceed.’’

Clarification of Type of Inspection 

We have clarified one of the 

inspection requirements contained in 

the proposed rule. Whereas paragraph 

(f)(1) of the proposed rule specifies a 

general visual inspection, we have 

revised paragraph (f)(1) of the final rule 

to clarify that our intent is to require a 

detailed inspection, as specified in the 

service bulletin. 

Conclusion 

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 changes 

previously described. The FAA has 

determined that these changes will 

neither increase the economic burden 

on any operator nor increase the scope 

of the AD. 

Changes to 14 CFR Part 39/Effect on the 

AD 

On July 10, 2002, the FAA issued a 

new version of 14 CFR part 39 (67 FR 

47997, July 22, 2002), which governs the 

FAA’s airworthiness directives system. 

The regulation now includes material 

that relates to altered products, special 

flight permits, and alternative methods 

of compliance. However, for clarity and 

consistency in this final rule, we have 

retained the language of the NPRM 

regarding that material. 

Change to Labor Rate Estimate 

We have reviewed the figures we have 

used over the past several years to 

calculate AD costs to operators. To 

account for various inflationary costs in 

the airline industry, we find it necessary 

to increase the labor rate used in these 

calculations from $60 per work hour to 

$65 per work hour. The cost impact 

information, below, reflects this 

increase in the specified hourly labor 

rate. 

Interim Action 

This is considered to be interim 

action for Group 7 airplanes. Although 

the service bulletin described 

previously does not include the 

inspection of the crown area (upper 

lobe) for Group 7 airplanes, as specified 

in paragraph (a) of this final rule, the 

manufacturer has advised that it 

currently is developing a new service 

bulletin to address those airplanes. 

Once the FAA has reviewed and 

approved the service bulletin, we may 

consider additional rulemaking to 

mandate those inspections. 

Cost Impact 

There are approximately 2,200 

airplanes of the affected design in the 

worldwide fleet. The FAA estimates that 

903 airplanes of U.S. registry will be 

affected by this proposed AD.

It will take approximately 94 work 

hours per airplane to accomplish the 

inspections of the crown area, at an 

average labor rate of $65 per work hour. 

Based on these figures, the cost impact 

of these inspections on U.S. operators is 

estimated to be $5,517,330, or $6,110 

per airplane, per inspection cycle. 

It will take approximately 96 work 

hours per airplane to accomplish the 

inspections of the lower lobe area, at an 

average labor rate of $65 per work hour. 

Based on these figures, the cost impact 

of these inspections on U.S. operators is 

estimated to be $5,634,720, or $6,240 

per airplane, per inspection cycle. 

The cost impact figures discussed 

above are based on assumptions that no 

operator has yet accomplished any of 

the requirements of this AD action, and 

that no operator would accomplish 

those actions in the future if this AD 

were not adopted. The cost impact 

figures discussed in AD rulemaking 

actions represent only the time 

necessary to perform the specific actions 

actually required by the AD. These 

figures typically do not include 

incidental costs, such as the time 

required to gain access and close up, 

planning time, or time necessitated by 

other administrative actions. 

Should an operator elect to install the 

preventive modification, it will take 

approximately 108 work hours to 

accomplish, at an average labor rate of 

$65 per work hour. Based on these 

figures, the cost impact of the 

preventive modification is estimated to 

be $7,020 per airplane. 

Regulatory Impact 

The regulations adopted herein will 

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. Therefore, it is 

determined that this final rule does not 

have federalism implications under 

Executive Order 13132. 

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.

54210 Federal Register / Vol. 69, No. 173 / Wednesday, September 8, 2004 / Rules and Regulations 

Adoption of the Amendment

■ Accordingly, pursuant to the authority 

delegated to me by the Administrator, 

the Federal Aviation Administration 

amends 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.

§ 39.13 [Amended]

■ 2. Section 39.13 is amended by adding 

the following new airworthiness 

directive:

2004–18–06 Boeing: Amendment 39–13784. 

Docket 2001–NM–246–AD.

Applicability: Model 737–200, –200C, 

–300, –400, and –500 series airplanes, as 

listed in Boeing Alert Service Bulletin 737–

53A1210, Revision 1, dated October 25, 2001; 

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 (j) 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 find and fix fatigue cracking of certain 

upper and lower skin panels of the fuselage, 

which could result in sudden fracture and 

failure of the skin panels and consequent 

rapid decompression of the airplane, 

accomplish the following: 

External Detailed and Eddy Current 

Inspections 

(a) For Groups 1 through 6 and Group 8 

airplanes: Before the accumulation of 35,000 

total flight cycles, or within 4,500 flight 

cycles after the effective date of this AD, 

whichever is later, do external detailed and 

eddy current inspections of the crown area 

and other known areas of fuselage skin 

cracking, per Part 1 and Figure 1 of the Work 

Instructions of Boeing Alert Service Bulletin 

737–53A1210, Revision 1, dated October 25, 

2001, except as provided by paragraph (i) of 

this AD. Repeat the external detailed and 

eddy current inspections at intervals not to 

exceed 4,500 flight cycles until paragraph (c), 

(d)(1)(ii), (e), (f), or (g) of this AD has been 

done, as applicable. Although paragraph 1.D. 

of the service bulletin references a reporting 

requirement, such reporting is not required 

by this AD.

Note 2: For the purposes of this AD, a 

detailed inspection is defined as: ‘‘An 

intensive visual examination of a specific 

structural area, system, installation, or 

assembly to detect damage, failure, or 

irregularity. Available lighting is normally 

supplemented with a direct source of good 

lighting at intensity deemed appropriate by 

the inspector. Inspection aids such as mirror, 

magnifying lenses, etc., may be used. Surface 

cleaning and elaborate access procedures 

may be required.’’

(b) For all airplanes: Before the 

accumulation of 40,000 total flight cycles, or 

within 4,500 flight cycles after the effective 

date of this AD, whichever is later, do an 

external detailed inspection of the lower lobe 

area and section 41 of the fuselage for 

cracking, per Part 2 and Figure 2 of the Work 

Instructions of Boeing Alert Service Bulletin 

737–53A1210, Revision 1, dated October 25, 

2001, except as provided by paragraph (i) of 

this AD. Repeat the inspection at intervals 

not to exceed 9,000 flight cycles until 

paragraph (d)(2) or (e) of this AD has been 

done, as applicable. 

Preventive Modification 

(c) For Groups 3, 5, 6, and 8 airplanes: If 

no cracking is found during any inspection 

required by paragraph (a) of this AD, doing 

the preventive modification of the chemmilled pockets in the upper skin as specified 

in Part 5 of the Work Instructions of Boeing 

Alert Service Bulletin 737–53A1210, 

Revision 1, dated October 25, 2001, ends the 

repetitive external detailed and eddy current 

inspections required by paragraph (a) of this 

AD for the modified area only. 

Corrective Actions 

(d) If any cracking is found during any 

inspection required by paragraph (a) or (b) of 

this AD, before further flight, do the actions 

specified in paragraphs (d)(1) and (d)(2) of 

this AD, as applicable, per the Work 

Instructions of Boeing Alert Service Bulletin 

737–53A1210, Revision 1, dated October 25, 

2001. Where the service bulletin specifies to 

contact Boeing for repair instructions, before 

further flight, repair per a method approved 

by the Manager, Seattle Aircraft Certification 

Office (ACO), FAA; or per data meeting the 

type certification basis of the airplane 

approved by a Boeing Company Designated 

Engineering Representative (DER) who has 

been authorized by the Manager, Seattle 

ACO, to make such findings. For a repair 

method to be approved by the Manager, 

Seattle ACO, as required by this paragraph, 

the approval letter must specifically 

reference this AD. 

(1) Except as provided by paragraph (e) of 

this AD, for cracking of the crown area, do 

the repair specified in either paragraph 

(d)(1)(i) or (d)(1)(ii) of this AD. 

(i) Do a time-limited repair per Part 4 of the 

Work Instructions of the service bulletin, 

then do the actions required by paragraph (f) 

of this AD at the times specified in that 

paragraph. 

(ii) Do a permanent repair per Part 3 of the 

Work Instructions of the service bulletin. 

Installation of a permanent repair ends the 

repetitive inspections required by paragraph 

(a) of this AD for the repaired area only. 

Installation of the lap joint repair specified in 

paragraph (g) of AD 2002–07–08, amendment 

39–12702, is considered acceptable for 

compliance with the corresponding 

permanent repair specified in this paragraph 

for the repaired areas only. 

(2) Except as provided by paragraph (e) of 

this AD, for cracking of the lower lobe area 

and Section 41, repair per Part 2 of the Work 

Instructions of the service bulletin. 

Accomplishment of this repair ends the 

repetitive inspections required by paragraph 

(b) of this AD for the repaired area only. 

Optional Repair Method 

(e) For cracking in any area specified in 

paragraphs (d)(1) and (d)(2) of this AD within 

the limitations of Chapter 53, Subject 53–30–

3, Figure 48 (for Model 737–100 and –200 

series airplanes), of the Boeing 737–100 and 

–200 Structural Repair Manual (SRM); 

Chapter 53, Subject 53–00–01, Figure 229 (for 

Model 737–300 airplanes), of the Boeing 

737–300 SRM; Chapter 53, Subject 53–00–01, 

Figure 231 (for Model 737–400 series 

airplanes), of the Boeing 737–400 SRM; and 

Chapter 53, Subject 53–00–01, Figure 229 (for 

Model 737–500 series airplanes), of the 

Boeing 737–500 SRM; repair cracks per the 

applicable SRM. Accomplishment of the 

applicable repair terminates the repetitive 

inspections required by paragraphs (a) and 

(b) of this AD for the repaired area only. 

Follow-on and Corrective Actions 

(f) If a time-limited repair is done, as 

specified in paragraph (d)(1)(i) of this AD: Do 

the actions specified in paragraphs (f)(1), 

(f)(2), and (f)(3) of this AD, at the times 

specified in paragraphs (f)(1), (f)(2), and (f)(3) 

of this AD, per the Work Instructions of 

Boeing Alert Service Bulletin 737–53A1210, 

Revision 1, dated October 25, 2001. 

(1) Within 3,000 flight cycles after doing 

the repair: Do a detailed inspection of the 

repaired area for loose fasteners per Part 4 of 

the Work Instructions of the service bulletin. 

If any loose fastener is found, before further 

flight, replace with a new fastener per the 

service bulletin. Then repeat the inspection 

at intervals not to exceed 3,000 flight cycles 

until permanent rivets are installed in the 

repaired area, which ends the repetitive 

inspections for this paragraph. 

(2) Within 4,000 flight cycles after doing 

the repair: Do inspections of the repaired area 

for cracking per Part 4 of the Work 

Instructions of the service bulletin. If any 

cracking is found, before further flight, repair 

per a method approved by the Manager, 

Seattle ACO, or per data meeting the type 

certification basis of the airplane approved 

by a Boeing Company DER who has been 

authorized by the FAA to make such 

findings. For a repair method to be approved 

by the Manager, Seattle ACO, as required by 

this paragraph, the approval letter must 

specifically reference this AD. 

(3) Within 10,000 flight cycles after doing 

the repair: Make the repair permanent per 

Part 4 and Figure 20 of the Work Instructions 

of the service bulletin, which ends the 

repetitive inspections for the repaired area 

only.

Federal Register / Vol. 69, No. 173 / Wednesday, September 8, 2004 / Rules and Regulations 54211

Optional Terminating Action for Repetitive 

Eddy Current Inspections 

(g) Accomplishment of paragraph (b) or (c), 

as applicable, of AD 2003–14–06, 

amendment 39–13225, ends the repetitive 

eddy current inspections required by 

paragraph (a) of this AD for that skin panel 

only; however the repetitive external detailed 

inspections required by paragraph (a) of this 

AD are still required for all areas.

Credit for Actions Done Per Previous Service 

Bulletin 

(h) Inspections, repairs, and preventive 

modifications done before the effective date 

of this AD per Boeing Alert Service Bulletin 

737–53A1210, dated December 14, 2000, are 

acceptable for compliance with the 

corresponding actions required by this AD. 

Exception to Service Bulletin Procedures 

(i) For airplanes subject to the 

requirements of paragraphs (a) and (b) of this 

AD: Inspections are not required in areas that 

are spanned by an FAA-approved repair that 

has a minimum of 3 rows of fasteners above 

and below the chem-milled step. If an 

external doubler covers the chem-milled 

step, but does not span it by a minimum of 

3 rows of fasteners above and below, in lieu 

of requesting approval for an alternative 

method of compliance (AMOC), one method 

of compliance with the inspection 

requirement of paragraphs (a) and (b) of this 

AD is to inspect all chemical-milled steps 

covered by the repair using internal 

nondestructive test (NDT) methods in 

accordance with Boeing 737 Non-Destructive 

Test NDT Manual, Part 6, Subject 53–30–20. 

Alternative Methods of Compliance 

(j)(1) An alternative method of compliance 

(AMOC) or adjustment of the compliance 

time that provides an acceptable level of 

safety may be used if approved by the 

Manager, Seattle ACO. 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. 

(2) AMOCs, approved previously in 

accordance with AD 2003–14–06, 

amendment 39–13225, for paragraphs (b) and 

(c) of AD 2003–14–06, are approved as 

AMOCs with paragraphs (a) and (g) of this 

AD for the applicable terminating action for 

the repetitive eddy current inspections only.

Note 3: Information concerning the 

existence of approved alternative methods of 

compliance with this AD, if any, may be 

obtained from the Seattle ACO.

Special Flight Permit 

(k) 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. 

Incorporation by Reference 

(l) Unless otherwise specified in this AD, 

the actions shall be done in accordance with 

Boeing Alert Service Bulletin 737–53A1210, 

Revision 1, dated October 25, 2001, 

excluding Appendix A. This incorporation 

by reference was approved by the Director of 

the Federal Register in accordance with 5 

U.S.C. 552(a) and 1 CFR part 51. Copies may 

be obtained from Boeing Commercial 

Airplanes, 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 National Archives and 

Records Administration (NARA). For 

information on the availability of this 

material at NARA, call (202) 741–6030, or go 

to: http://www.archives.gov/federal_register/

code_of_federal_regulations/

ibr_locations.html.

Effective Date 

(m) This amendment becomes effective on 

October 13, 2004.

Issued in Renton, Washington, on August 

26, 2004. 

Kevin M. Mullin, 

Acting Manager, Transport Airplane 

Directorate, Aircraft Certification Service.

[FR Doc. 04–20120 Filed 9–7–04; 8:45 am] 

BILLING CODE 4910–13–P

DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration 

14 CFR Part 39 

[Docket No. 2003–NM–131–AD; Amendment 

39–13786; AD 2004–18–08] 

RIN 2120–AA64 

Airworthiness Directives; Boeing 

Model 727, 727C, 727–100, –100C, and 

–200 Series Airplanes

AGENCY: Federal Aviation 

Administration, DOT.

ACTION: Final rule.

SUMMARY: This amendment adopts a 

new airworthiness directive (AD), 

applicable to certain Boeing Model 727, 

727C, 727–100, –100C, and –200 series 

airplanes. This amendment requires an 

inspection of the forward trunnion 

attach fittings of the main landing gear 

(MLG), inspections of the attach fitting 

holes of the forward trunnion attach 

fittings if necessary, replacement of the 

forward trunnion attach fittings if 

necessary, and corrective actions if 

necessary. This action is necessary to 

detect and correct cracks and corrosion 

on the attach fitting holes of the forward 

trunnion attach fittings of the MLG, 

which could result in the collapse of the 

MLG. This action is intended to address 

the identified unsafe condition.

DATES: Effective October 13, 2004. 

The incorporation by reference of a 

certain publication listed in the 

regulations is approved by the Director 

of the Federal Register as of October 13, 

2004.

ADDRESSES: The service information 

referenced in this AD may be obtained 

from Boeing Commercial Airplanes, 

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 National Archives 

and Records Administration (NARA). 

For information on the availability of 

this material at NARA, call (202) 741–

6030, or go to: http://www.archives.gov/

federal_register/

code_of_federal_regulations/

ibr_locations.html.

FOR FURTHER INFORMATION CONTACT:

Daniel F. Kutz, Aerospace Engineer, 

Airframe Branch, ANM–120S, FAA, 

Seattle Aircraft Certification Office, 

1601 Lind Avenue, SW., Renton, 

Washington 98055–4056; telephone 

(425) 917–6456; fax (425) 917–6590.

SUPPLEMENTARY INFORMATION: A 

proposal to amend part 39 of the Federal 

Aviation Regulations (14 CFR part 39) to 

include an airworthiness directive (AD) 

that is applicable to certain Boeing 

Model 727, 727C, 727–100, –100C, and 

–200 series airplanes was published in 

the Federal Register on June 16, 2004 

(69 FR 33587). That action proposed to 

require an inspection of the forward 

trunnion attach fittings of the main 

landing gear, inspections of the attach 

fitting holes of the forward trunnion 

attach fittings if necessary, replacement 

of the forward trunnion attach fittings if 

necessary, and corrective actions if 

necessary. 

Comments 

Interested persons have been afforded 

an opportunity to participate in the 

making of this amendment. Due 

consideration has been given to the 

single comment received. 

The commenter supports the 

proposed rule. 

Conclusion 

After careful review of the available 

data, including the comment noted 

above, the FAA has determined that air 

safety and the public interest require the 

adoption of the rule as proposed. 

Cost Impact 

There are approximately 523 

airplanes of the affected design in the 

worldwide fleet. The FAA estimates that 

309 airplanes of U.S. registry will be 

affected by this AD, that it will take 

approximately 1 work hour per airplane 

to accomplish the required inspection, 

and that the average labor rate is $65 per 

work hour. Based on these figures, the