[Federal Register Volume 66, Number 78 (Monday, April 23, 2001)]
[Rules and Regulations]
[Pages 20380-20383]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 01-9664]


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

DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 2000-NM-295-AD; Amendment 39-12184; AD 2001-08-07]
RIN 2120-AA64


Airworthiness Directives; Boeing Model 737-200 and -300 Series 
Airplanes Equipped with a Main Deck Cargo Door Installed in Accordance 
with Supplemental Type Certificate (STC) SA2969SO

AGENCY: Federal Aviation Administration, DOT.

ACTION: Final rule.

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

SUMMARY: This amendment supersedes an existing airworthiness directive 
(AD), applicable to certain Boeing Model 737-200 and -300 series 
airplanes, that currently requires a one-time inspection to detect 
cracks of the lower frames and reinforcing angles of the main deck 
cargo door where the door latch fittings attach between certain 
fuselage stations and water lines, and replacement of any cracked part 
with a new part having the same part number. That AD was prompted by 
reports that, during the inspections required by the existing AD, 
cracks were found in the reinforcing angles of the main deck cargo door 
frame. This amendment requires, among other actions, an inspection to 
detect cracks of the lower frames and

[[Page 20381]]

reinforcing angles of the main deck cargo door; replacement of any 
lower frame or reinforcing angle of the main deck cargo door when it 
has reached its maximum life limit. The actions specified by this AD 
are intended to detect and correct cracking of the lower portion of the 
main deck cargo door frames, which could result in sudden 
depressurization, loss or opening of the main deck cargo door during 
flight, and loss of control of the airplane.

DATES: Effective May 29, 2001.
    The incorporation by reference of certain publications listed in 
the regulations is approved by the Director of the Federal Register as 
of May 29, 2001.

ADDRESSES: The service information referenced in this AD may be 
obtained from Pemco World Air Services, 100 Pemco Drive, Dothan, AL 
36303. 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 FAA, Atlanta 
Aircraft Certification Office, One Crown Center, 1895 Phoenix 
Boulevard, Suite 450, Atlanta, Georgia; or at the Office of the Federal 
Register, 800 North Capitol Street, NW., suite 700, Washington, DC.

FOR FURTHER INFORMATION CONTACT: William Culler, Aerospace Engineer, 
Airframe and Propulsion Branch, ACE-117A, FAA, Atlanta Aircraft 
Certification Office, One Crown Center, 1895 Phoenix Boulevard, Suite 
450, Atlanta, Georgia 30337-2748, telephone (770) 703-6084; fax (770) 
703-6097.

SUPPLEMENTARY INFORMATION: A proposal to amend part 39 of the Federal 
Aviation Regulations (14 CFR part 39) by superseding AD 2000-17-51, 
amendment 39-11877 (65 FR 51752, August 25, 2000), which is applicable 
to certain Boeing Model 737-200 and -300 series airplanes, was 
published in the Federal Register on October 17, 2000 (65 FR 61289). 
The action proposed to require, among other actions, an inspection to 
detect cracks of the lower frames and reinforcing angles of the main 
deck cargo door; replacement of any lower frame or reinforcing angle of 
the main deck cargo door when it has reached its maximum life limit.

Comments Received

    Interested persons have been afforded an opportunity to participate 
in the making of this amendment. Due consideration has been given to 
the comments received.

Request to Change Proposed High Frequency Eddy Current (HFEC) 
Inspections to Detailed Visual Inspections

    One commenter requests that, in lieu of the proposed repetitive 
HFEC inspections, repetitive detailed visual inspections with a 
borescope, flexiscope, or mirror and light be required every 600 flight 
cycles for cracks in the frames and, especially, in the reinforcing 
angles, provided that the initial inspection was an HFEC inspection of 
all lower frames and angles and all parts with crack indication were 
replaced with new parts. The commenter states that this change would 
alleviate the need to remove and reinstall the necessary hardware 
required to perform an adequate HFEC inspection, which causes an 
extended fleet downtime and damages the area being inspected. The 
commenter also states that it has reviewed statistical data from its 
fleet of airplanes on which HFEC inspections were done per AD 2000-17-
51 that shows the number of cracked angles is higher than the number of 
cracked frames at the same frame station. Based on this data, the 
commenter provided a graph that shows a close correlation between 
cracked frames and attached angles.
    The FAA does not agree. As indicated in the preamble of AD 2000-17-
51, the special detailed visual inspection done per AD 2000-13-51 is 
not adequate to detect cracks embedded behind the reinforcing angles. 
In addition, previous reports from the commenter's fleet, and other 
operators, indicate that cracks could exist on a frame and remain 
hidden behind uncracked reinforcing angles. Therefore, we find that the 
required repetitive HFEC inspections are warranted to address the 
identified unsafe condition.

Request to Revise Wording of Paragraph (b)(2) of the Proposed AD

    One commenter requests that paragraph (b)(2) of the proposed AD be 
revised to ``* * * replace the frames and associated angles which were 
not changed as per AD 2000-17-51 * * * Within 3,000 flight cycles after 
accomplishment of the replacement of parts as per 2000-NM-295-AD, do 
the HFEC inspection required of all the frames and associated angles.'' 
The commenter states that revising ``reinforcing angle'' to 
``associated angle'' is necessary, because the terminating action, 
which is being developed, relies on a new angle (reinforcing angle) 
located on top of the existing angle (associated angle of the frame).
    The FAA does not agree. We find that adding the phrase ``which were 
not changed per AD 2000-17-51'' is unnecessary, because paragraph (b) 
of the final rule clearly identifies the affected airplanes as those 
``on which any door frame or reinforcing angle at the location where 
the door latch fittings attach between FS 361.86 and FS 298.12 and WL 
202.35 and WL 213.00 has NOT been replaced before the effective date of 
this AD.'' In addition, the header of paragraph (b) of the final rule 
is ``Actions Addressing Door Frames or Reinforcing Angles That Have NOT 
Been Replaced.'' We also find that adding the phrase ``as per 2000-NM-
295-AD'' to the compliance time of ``within 3,000 flight cycles after 
accomplishment of the replacement'' is unnecessary and redundant as the 
``Compliance'' section of this AD states, ``Required as indicated, 
unless previously accomplished.'' We note that the docket number 
associated with the preceding NPRM and this final rule is 2000-NM-295-
AD. Furthermore, the term ``reinforcing angle'' is used in the design 
data and service documents of the original equipment manufacturer and 
in preceding AD's. Therefore, based on these conclusions, we find that 
no change is necessary to paragraph (b)(2) of the final rule.

Requests to Reference or Develop Terminating Action

    One commenter requests that the airplane manufacturer develop a 
terminating modification for the repetitive inspections required by the 
proposed AD. A second commenter requests that the proposed AD reference 
Pemco Service Bulletin 737-52-0036 as terminating action for the 
repetitive requirements of the proposed AD. A third commenter, Pemco, 
states that it is currently developing two terminating actions, and 
that they will be approved by a Designated Engineering Representative 
in November and December 2000. One commenter states that the proposed 
repetitive inspections requires removal and reinstallation of hardware, 
which can reduce fastener edge distance and potentially cause damage to 
the inspected areas. The commenter also states that these inspections 
cause unscheduled downtimes up to four weeks per airplane.
    The FAA agrees with the commenters that a terminating action is 
desireable. However, we do not agree with the commenters' concern that 
the required inspections and reinstallation of hardware may result in 
potential

[[Page 20382]]

damage to the inspected area, since we anticipate that the terminating 
action will be available before the accomplishment of multiple 
inspections. We are aware that the affected Supplemental Type 
Certificate (STC) holder is developing service bulletin procedures to 
address the identified unsafe condition. However, the service bulletins 
are not scheduled to be completed until mid 2001. We have decided not 
to delay this action in anticipation of the service bulletins, since 
the release date is not absolute and this action is necessary to 
address an identified unsafe condition. Therefore, the FAA may approve 
requests for an alternative method of compliance (AMOC) under the 
provisions of paragraph (c) of this AD once the revised bulletins are 
issued. No change to the final rule is necessary.

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 as proposed.

Cost Impact

    There are approximately 35 Model 737-200 and -300 series airplanes 
of the affected design in the worldwide fleet. The FAA estimates that 2 
airplanes of U.S. registry will be affected by this AD.
    It will take approximately 500 work hours per airplane to 
accomplish the inspection, at an average labor rate of $60 per work 
hour. Based on these figures, the cost impact of the inspection 
required by this AD on U.S. operators is estimated to be $60,000, or 
$30,000 per airplane.
    It will take approximately 128 work hours per airplane to 
accomplish the replacement, at an average labor rate of $60 per work 
hour. Required parts will cost approximately $15,521 per airplane. 
Based on these figures, the cost impact of the replacement required by 
this AD on U.S. operators is estimated to be $46,402, or $23,201 per 
airplane.
    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.

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.

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.


Sec. 39.13  [Amended]

    2. Section 39.13 is amended by removing amendment 39-11877 (65 FR 
51752, August 25, 2000), and by adding a new airworthiness directive 
(AD), amendment 39-12184, to read as follows:

2001-08-07  Boeing: Amendment 39-12184. Docket 2000-NM-295-AD. 
Supersedes AD 2000-17-51, Amendment 39-11877.

    Applicability: Model 737-200 and -300 series airplanes, equipped 
with a main deck cargo door installed in accordance with 
Supplemental Type Certificate (STC) SA2969SO; certificated in any 
category.

    Note 1: This AD applies to each airplane identified in the 
preceding applicability provision, regardless of whether it has been 
otherwise modified, altered, or repaired in the area subject to the 
requirements of this AD. For airplanes that have been modified, 
altered, or repaired so that the performance of the requirements of 
this AD is affected, the owner/operator must request approval for an 
alternative method of compliance in accordance with paragraph (c)(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 cracking of the lower portion of the main 
deck cargo door frames, which could result in sudden 
depressurization, loss or opening of the main deck cargo door during 
flight, and loss of control of the airplane, accomplish the 
following:

Actions Addressing Door Frames or Reinforcing Angles That Have Been 
Replaced

    (a) For airplanes on which any door frame or reinforcing angle 
at the location where the door latch fittings attach between 
fuselage station (FS) 361.86 and FS 298.12 and water line (WL) 
202.35 and WL 213.00 has been replaced before the effective date of 
this AD: Do the actions specified in paragraphs (a)(1) and (a)(2) of 
this AD per the Accomplishment Instructions of Pemco Service 
Bulletin 737-52-0037, Revision 2, dated September 13, 2000, 
including Attachment 1, dated August 10, 2000.
    (1) Within 3,000 flight cycles after accomplishment of the 
replacement, do a high frequency eddy current (HFEC) inspection to 
detect cracks of the replaced lower frames or replaced reinforcing 
angles of the main deck cargo door, as applicable.
    (i) If no crack is detected, repeat the HFEC inspection 
thereafter at intervals of 1,300 flight cycles on the replaced part.
    (ii) If any crack is detected, before further flight, replace 
the cracked part with a new part having the same part number per the 
service bulletin. Within 3,000 flight cycles after accomplishment of 
the replacement, do the HFEC inspection required by paragraph (a)(1) 
of this AD.
    (2) Before or upon the accumulation of 7,000 total flight cycles 
on any lower frame or reinforcing angle of the main deck cargo door, 
replace the lower frame or reinforcing angle, as applicable, with 
new parts. Within 3,000 flight cycles after accomplishment of the 
replacement, do the HFEC inspection required by paragraph (a)(1) of 
this AD.

Actions Addressing Door Frames or Reinforcing Angles That Have NOT Been 
Replaced

    (b) For airplanes on which any door frame or reinforcing angle 
at the location where the door latch fittings attach between FS 
361.86 and FS 298.12 and WL 202.35 and WL 213.00 has NOT been 
replaced before the effective date of this AD: Within 1,300 flight 
cycles after accomplishment of the HFEC inspection required by AD 
2000-17-51, amendment 39-11877, do the action specified in either 
paragraph (b)(1) or (b)(2) of this AD, as applicable, per the 
Accomplishment

[[Page 20383]]

Instructions of Pemco Service Bulletin 737-52-0037, Revision 2, 
dated September 13, 2000, including Attachment 1, dated August 10, 
2000.
    (1) For airplanes that have accumulated less than 7,000 total 
flight cycles since installation of STC SA2969SO: Do an HFEC 
inspection to detect cracks of the lower frames and reinforcing 
angles of the main deck cargo door where the door latch fittings 
attach between FS 361.87 and FS 498.12 and WL 202.35 and WL 213.00.
    (i) If no crack is detected, do the actions specified in 
paragraphs (b)(1)(i)(A) and (b)(1)(i)(B) of this AD.
    (A) Repeat the HFEC inspection thereafter at intervals of 1,300 
flight cycles on the airplane, but not to exceed the accumulation of 
7,000 total flight cycles on the airplane.
    (B) Before the accumulation of 7,000 total flight cycles on the 
airplane, replace the lower frame and reinforcing angle with new 
parts per the service bulletin. Within 3,000 flight cycles after 
accomplishment of the replacement, do the HFEC inspection required 
by paragraph (a)(1) of this AD.
    (ii) If any crack is detected, before further flight, replace 
the cracked part with a new part having the same part number per the 
service bulletin. Within 3,000 flight cycles after accomplishment of 
the replacement, do the HFEC inspection required by paragraph (a)(1) 
of this AD.
    (2) For airplanes that have accumulated 7,000 or more total 
flight cycles since installation of STC SA2969SO: Replace the lower 
frames and reinforcing angles with new parts. Within 3,000 flight 
cycles after accomplishment of the replacement, do the HFEC 
inspection required by paragraph (a)(1) of this AD.

Alternative Methods of Compliance

    (c)(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, Atlanta Aircraft Certification 
Office (ACO), FAA. Operators shall submit their requests through an 
appropriate FAA Principal Maintenance Inspector, who may add 
comments and then send it to the Manager, Atlanta ACO.

    Note 2: Information concerning the existence of approved 
alternative methods of compliance with this AD, if any, may be 
obtained from the Atlanta ACO.

    (2) Alternative methods of compliance, approved previously in 
accordance with AD 2000-17-51, amendment 39-11877, are approved as 
alternative methods of compliance with the initial HFEC inspection 
required by paragraph (a)(1) of this AD.

Special Flight Permits

    (d) Special flight permits may be issued in accordance with 
Secs. 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

    (e) The actions shall be done in accordance with Pemco Service 
Bulletin 737-52-0037, Revision 2, dated September 13, 2000, 
including Attachment 1, dated August 10, 2000, which contains the 
list of effective pages specified in Table 1 of this AD. Table 1 is 
as follows:

                                Table 1.
------------------------------------------------------------------------
                                    Revision level
           Page number               shown on page    Date shown on page
------------------------------------------------------------------------
1...............................  A.................  August 15, 2000.
2, 3, 6-10......................  Original..........  August 10, 2000.
4, 4a, 5........................  2.................  September 13,
                                                       2000.
Attachment 1, 2.................  Original..........  August 10, 2000.
------------------------------------------------------------------------

    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 Pemco World Air Services, 100 
Pemco Drive, Dothan, AL 36303. Copies may be inspected at the FAA, 
Transport Airplane Directorate, 1601 Lind Avenue, SW., Renton, 
Washington; or at the FAA, Atlanta Aircraft Certification Office, 
One Crown Center, 1895 Phoenix Boulevard, Suite 450, Atlanta, 
Georgia; or at the Office of the Federal Register, 800 North Capitol 
Street, NW., suite 700, Washington, DC.

Effective Date

    (f) This amendment becomes effective on May 29, 2001.

    Issued in Renton, Washington, on April 12, 2001.
Donald L. Riggin,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 01-9664 Filed 4-20-01; 8:45 am]
BILLING CODE 4910-13-U