[Federal Register Volume 62, Number 18 (Tuesday, January 28, 1997)]
[Rules and Regulations]
[Pages 3988-3991]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 97-1440]


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DEPARTMENT OF TRANSPORTATION
14 CFR Part 39

[Docket No. 95-NM-223-AD; Amendment 39-9894; AD 97-02-09]
RIN 2120-AA64


Airworthiness Directives; Boeing Model 727 Series Airplanes

AGENCY: Federal Aviation Administration, DOT.

ACTION: Final rule.

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SUMMARY: This amendment supersedes two existing airworthiness 
directives (AD), applicable to all Boeing Model 727 series airplanes, 
that currently require inspections to detect cracking of the actuator 
rib fitting of the inboard door of the main landing gear (MLG); and 
rework or replacement of any cracked fitting. This amendment requires 
inspections to detect cracking in an expanded area of the actuator rib 
fitting, and various follow-on actions. This amendment is prompted by a 
report of a fractured rib fitting that had been reworked in accordance 
with one of the existing AD's. The actions specified by this AD are 
intended to prevent damage to the airplane caused by a failure of the 
landing gear to extend due to a fractured rib fitting.

DATES: Effective March 4, 1997.
    The incorporation by reference of certain publications listed in 
the regulations is approved by the Director of the Federal Register as 
of March 4, 1997.

ADDRESSES: The service information referenced in this AD may be 
obtained from Boeing Commercial Airplane Group, 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 Office of 
the Federal Register, 800 North Capitol Street, NW., suite 700, 
Washington, DC.

FOR FURTHER INFORMATION CONTACT: Walter Sippel, Aerospace Engineer, 
Airframe Branch, ANM-120S, FAA, Seattle Aircraft Certification Office, 
1601 Lind Avenue, SW., Renton, Washington; telephone (206) 227-2774; 
fax (206) 227-1181.

SUPPLEMENTARY INFORMATION: A proposal to amend part 39 of the Federal 
Aviation Regulations (14 CFR part 39) by superseding AD 90-02-19 
[amendment 39-6433 (55 FR 601, January 8, 1990)] and AD 93-01-14 
[amendment 39-8368, (58 FR 5574, January 22, 1993)], both of which are 
applicable to Boeing Model 727 series airplanes, was published in the 
Federal Register as a supplemental notice of proposed rulemaking on 
October 1, 1996,(61 FR 51250). The action proposed to continue to 
require the actions specified in the two previously issued AD's, but to 
expand the area of inspection and to require various follow-on actions.
    Interested persons have been afforded an opportunity to participate 
in the making of this amendment. Due consideration has been given to 
the comments received.

Support for the Proposal

    Two commenters support the proposed AD.

Request To Revise Compliance Threshold for Modified Fittings

    One commenter, the airframe manufacturer, requests that paragraph 
(b)(1)(ii) of the proposal be revised to extend one of the compliance 
thresholds for the initial inspections of fittings that have been 
modified in accordance with Boeing Service bulletin 727-32-0383, 
Revision 1. This commenter points out that, in the supplemental NPRM, 
the FAA proposed to reduced the initial

[[Page 3989]]

inspection time for these fittings from 2,500 cycles to 1,500 cycles, 
based on an analysis of a recent incident of cracking found in the 
fittings. However, based on newer data, the commenter states that the 
proposed reduction may be too conservative. A recent striation analysis 
has shown that the crack on the fitting involved in the new incident 
was present for a significantly greater time than the 1,350 cycles 
since the last inspection (as originally thought). The exact interval 
between crack initiation and fitting fracture is indeterminate because 
of fracture surface deterioration. There was evidence of significant 
surface attack, which indicates prolonged exposure to a corrosive 
environment; however, the exact length of exposure is not known. The 
commenter further states that it was possible to perform some striation 
count analysis on a portion of the fracture; correlation of this 
analysis to the analysis performed on the earlier cracking incident (in 
1994) showed a high degree of similarity. Additionally, the commenter 
states that the recent cracking incident occurred approximately 8,000 
cycles after the modification was installed on the fitting. 
Consequently, the commenter considers that the reasoning for a 2,500-
cycle initial inspection threshold is valid.
    The FAA concurs. The FAA has reviewed the data presented by the 
commenter and agrees that the threshold for initiating the inspections 
of modified fittings can be extended. Paragraph (b)(1)(ii) of the final 
rule has been revised to indicate a threshold of 2,500 flight cycles 
after the immediately preceding inspection conducted in accordance with 
Boeing Service Bulletin 727-32A0399. Additionally, a new paragraph 
(b)(1)(iii) has been added to provide for a threshold of ``within 5,000 
flight cycles after accomplishing the terminating action in accordance 
with AD 93-01-14.''

Request for Reference to Additional Service Information

    This same commenter, requests that the proposal be revised to 
include Revision 1 of Boeing Service Bulletin 727-32A0399 as an 
additional source of service information. The commenter indicates that 
Boeing will be issuing Revision 1 of the service bulletin in the near 
future to reflect the requirements and reference the AD number of this 
final rule.
    The FAA does not concur, since Revision 1 does not yet exist and 
has not been reviewed and approved by the FAA.

Request to Revise Cost Impact Information

    One commenter requests that the cost impact information, iterated 
in the preamble to the supplemental NPRM, be revised to update the cost 
of required parts for the optional terminating action (installation of 
steel fittings). This commenter states that the necessary parts cost 
$3,489 per side and there are two sides; therefore, the total cost of 
parts is $6,978. Additionally, the commenter points out that the number 
of work hours required to accomplish the installation is 18, rather 
than 4 work hours, as was indicated in the proposal.
    The FAA concurs that the figures provided by the commenter are more 
up-to-date than those obtained by the FAA at the time the supplemental 
NPRM was issued. The cost impact information, below, has been revised 
to include these new figures.

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.

Cost Impact

    There are approximately 1,631 Boeing Model 727 series airplanes of 
the affected design in the worldwide fleet. The FAA estimates that 
1,166 airplanes of U.S. registry will be affected by this proposed AD.
    The inspections required by this AD action will take approximately 
10 work hours per airplane to accomplish, at an average labor rate of 
$60 per work hour. Based on these figures, the cost impact of the 
required inspections on U.S. operators is estimated to be $699,600, or 
$600 per airplane, per inspection.
    The modification required by this AD action will take approximately 
6 work hours per airplane to accomplish, at an average labor rate of 
$60 per work hour. The cost of required parts is expected to be 
negligible. Based on these figures, the cost impact of the required 
modification on U.S. operators is estimated to be $376,560, or $360 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.
    Should an operator elect to accomplish the optional terminating 
action (installation of steel fittings) provided by this AD, it would 
take approximately 18 work hours per airplane, at an average labor rate 
of $60 per work hour. Required parts would cost approximately $6,978 
per airplane. Based on these figures, the cost impact of this optional 
terminating action on U.S. operators is estimated to be $8,058 per 
airplane.

Regulatory Impact

    The regulations adopted herein will not have substantial direct 
effects on the States, on the relationship between the national 
government and the States, or on the distribution of power and 
responsibilities among the various levels of government. Therefore, in 
accordance with Executive Order 12612, it is determined that this final 
rule does not have sufficient federalism implications to warrant the 
preparation of a Federalism Assessment.
    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 39-6433 (55 FR 
601, January 8, 1990); and by removing amendment 39-8368 (58 FR 5574, 
January 22, 1993); and by adding a new

[[Page 3990]]

airworthiness directive (AD), to read as follows:

97-02-09 Boeing: Amendment 39-9894, Docket 95-NM-223-AD. Supersedes 
AD 90-02-19, amendment 39-6433; and supersedes AD 93-01-14, 
amendment 39-8368.

    Applicability: All Model 727 series airplanes, certificated in 
any category.

    Note 1: This AD applies to each airplane identified in the 
preceding applicability provision, regardless of whether it has been 
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 (g) of 
this AD. The request should include an assessment of the effect of 
the modification, alteration, or repair on the unsafe condition 
addressed by this AD; and, if the unsafe condition has not been 
eliminated, the request should include specific proposed actions to 
address it.
    Compliance: Required as indicated, unless accomplished 
previously.
    To prevent failure of the main landing gear (MLG) to extend for 
landing and subsequent damage to the airplane, accomplish the 
following:
    (a) For airplanes equipped with rib fittings that have been 
modified (reworked) in accordance with Boeing Service Bulletin 727-
32-0364, dated December 15, 1988, or Revision 1, dated October 19, 
1989; but have not been modified in accordance with Figure 2 of 
Boeing Service Bulletin 727-32-0383, Revision 1, dated January 30, 
1992: Accomplish the following:
    (1) Prior to the accumulation of 1,000 flight cycles after the 
effective date of this AD, accomplish the actions specified in both 
paragraphs (a)(1)(i) and (a)(1)(ii):
    (i) Perform either a high frequency eddy current or dye 
penetrant inspection to detect cracking of the actuator rib fitting 
of the MLG, in accordance with Part I of the Accomplishment 
Instructions of Boeing Alert Service Bulletin 727-32A0399, dated 
July 13, 1995. And
    (ii) Inspect the actuator rib fitting of the MLG to ensure that 
serrations are fully mated, and to detect loose bolts, in accordance 
with Figure 1 of Boeing Service Bulletin 727-32-0383, Revision 1, 
dated January 30, 1992.
    (2) If the inspections required by paragraph (a)(1) of this AD 
reveal no cracking or loose bolts, and reveal that the serrations 
are fully mated, accomplish the actions specified in paragraphs 
(a)(2)(i), (a)(2)(ii), and (a)(2)(iii) of this AD:
    (i) Prior to further flight, re-rig the door in accordance with 
the maintenance manual procedures referenced in Boeing Alert Service 
Bulletin 727-32A0399, dated July 13, 1995, to ensure proper door 
rigging. And
    (ii) Thereafter, repeat the inspections required by paragraph 
(a)(1) of this AD at intervals not to exceed 1,000 flight cycles 
until the modification required by paragraph (a)(2)(iii) of this AD 
is accomplished; and
    (iii) Prior to the accumulation of 3,000 flight cycles after the 
effective date of this AD, modify the actuator rib fitting in 
accordance with Part II of the Accomplishment Instructions of Boeing 
Alert Service Bulletin 727-32A0399, dated July 13, 1995. As an 
option to the action specified in Step 1 of Figure 3 of that alert 
service bulletin, operators may layout a .39-inch minimum radius.
    (3) If the inspections required by paragraph (a)(1) of this AD 
reveal no cracking, but do reveal loose bolts or serrations that are 
not fully mated, prior to further flight accomplish either paragraph 
(a)(3)(i) or (a)(3)(ii) of this AD:
    (i) Modify the actuator rib fitting in accordance with Part II 
of the Accomplishment Instructions of Boeing Alert Service Bulletin 
727-32A0399, dated July 13, 1995. As an option to the action 
specified in Step 1 of Figure 3 of that alert service bulletin, 
operators may layout a .39-inch minimum radius; or
    (ii) Replace the currently-installed aluminum rib fitting with a 
new steel rib fitting, in accordance with Part III of the 
Accomplishment Instructions of Boeing Alert Service Bulletin 727-
32A0399, dated July 13, 1995. After this replacement, no further 
action is required by this AD for that rib fitting.
    (b) For airplanes equipped with rib fittings that have been 
modified in accordance with Boeing Service Bulletin 727-32-0364, 
dated December 15, 1988, or Revision 1, dated October 19, 1989; and 
have been modified in accordance with Figure 2 of Boeing Service 
Bulletin 727-32-0383, Revision 1, dated January 30, 1992: Accomplish 
the following:
    (1) Perform either a high frequency eddy current or dye 
penetrant inspection to detect cracking of the actuator rib fitting 
of the MLG, in accordance with Part I of the Accomplishment 
Instructions of Boeing Alert Service Bulletin 727-32A0399, dated 
July 13, 1995, at the later of the times specified in either 
paragraph (b)(1)(i), (b)(1)(ii), or (b)(1)(iii) of this AD.
    (i) Prior to the accumulation of 1,000 flight cycles after the 
effective date of the AD; or
    (ii) Within 2,500 flight cycles after the immediately preceding 
inspection performed in accordance with Boeing Service Bulletin 727-
32A0399; or
    (iii) Within 5,000 flight cycles after accomplishing the 
terminating action in accordance with AD 93-01-14.
    (2) If no cracking is detected during the inspection required by 
paragraph (b)(1) of this AD, accomplish the actions specified in 
paragraphs (b)(2)(i), (b)(2)(ii), and (b)(2)(iii) of this AD:
    (i) Prior to further flight, re-rig the door in accordance with 
the maintenance manual procedures referenced in Boeing Alert Service 
Bulletin 727-32A0399, dated July 13, 1995, to ensure proper door 
rigging; and
    (ii) Thereafter, repeat the inspection required by paragraph 
(b)(1) at intervals not to exceed 2,500 flight cycles until the 
modification required by paragraph (b)(2)(iii) of this AD is 
accomplished; and
    (iii) Prior to the accumulation of 6,000 flight cycles after the 
effective date of this AD, modify the actuator rib fitting in 
accordance with Part II of the Accomplishment Instructions of Boeing 
Alert Service Bulletin 727-32A0399, dated July 13, 1995. As an 
option to the action specified in Step 1 of Figure 3 of that alert 
service bulletin, operators may layout a .39-inch minimum radius.
    (c) For airplanes equipped with rib fittings that have not been 
modified in accordance with Boeing Service Bulletin 727-32-0364, 
dated December 15, 1988, or Revision 1, dated October 19, 1989: 
Accomplish the following:
    (1) Prior to the accumulation of 1,000 flight cycles after the 
effective date of this AD, accomplish the actions specified in both 
paragraphs (c)(1)(i) and (c)(1)(ii) of this AD:
    (i) Perform either a high frequency eddy current or dye 
penetrant inspection to detect cracking of the actuator rib fitting 
of the MLG, in accordance with Part I of the Accomplishment 
Instructions of Boeing Alert Service Bulletin 727-32A0399, dated 
July 13, 1995. And
    (ii) Inspect the actuator rib fitting of the MLG to ensure that 
serrations are fully mated, and to detect loose bolts, in accordance 
with Figure 1 of Boeing Service Bulletin 727-32-0383, Revision 1, 
dated January 30, 1992.
    (2) If the inspections required by paragraph (c)(1) of this AD 
reveal no cracking or loose bolts, and reveal that the serrations 
are fully mated, prior to further flight, accomplish the actions 
specified in either paragraph (c)(2)(i), (c)(2)(ii), or (c)(2)(iii) 
of this AD:
    (i) Modify the actuator rib fitting in accordance with Part II 
of the Accomplishment Instructions of Boeing Alert Service Bulletin 
727-32A0399, dated July 13, 1995; and in accordance with Boeing 
Service Bulletin 727-32-0364, dated December 15, 1988, or Revision 
1, dated October 19, 1989. As an option to the action specified in 
Step 1 of Figure 3 of Boeing Alert Service Bulletin 727-32A0399, 
operators may layout a .39-inch minimum radius; or
    (ii) Replace the currently-installed aluminum rib fitting with a 
new steel rib fitting, in accordance with Part III of the 
Accomplishment Instructions of Boeing Alert Service Bulletin 727-
32A0399, dated July 13, 1995. After this replacement, no further 
action is required by this AD for that fitting; or
    (iii) Replace the fitting with a like fitting that has been 
inspected in accordance with Part I of the Accomplishment 
Instructions of Boeing Alert Service Bulletin 727-32A0399, dated 
July 13, 1995; and modified in accordance with Part II of the 
Accomplishment Instructions of that service bulletin and in 
accordance with Boeing Service Bulletin 727-32-0364, dated December 
15, 1988, or Revision 1, dated October 19, 1989.
    (d) If any cracking is detected during the inspections required 
by paragraphs (a)(1), (b)(1), or (c)(1) of this AD, prior to further 
flight, accomplish the actions specified in either paragraph (d)(1) 
or (d)(2) of this AD:
    (1) Replace the cracked fitting with a like fitting that has 
been inspected in accordance with Part I of the Accomplishment 
Instructions of Boeing Alert Service Bulletin 727-32A0399, dated 
July 13, 1995; and modified in accordance with Part II of the 
Accomplishment Instructions of that service

[[Page 3991]]

bulletin and in accordance with Boeing Service Bulletin 727-32-0364, 
dated December 15, 1988, or Revision 1, dated October 19, 1989. As 
an option to the action specified in Step 1 of Figure 3 of Boeing 
Alert Service Bulletin 727-32A0399, operators may layout a .39-inch 
minimum radius; or
    (2) Replace the cracked fitting with a new steel rib fitting in 
accordance with Part III of the Accomplishment Instructions of 
Boeing Alert Service Bulletin 727-32A0399, dated July 13, 1995. This 
replacement constitutes terminating action for the requirements of 
that AD for that fitting.
    (e) For all airplanes on which modification of the actuator rib 
fitting has been accomplished in accordance with Part II of the 
Accomplishment Instructions of Boeing Alert Service Bulletin 727-
32A0399, dated July 13, 1995; and Boeing Service Bulletin 727-32-
0364, dated December 15, 1988, or Revision 1, dated October 19, 
1989: Within 7,500 flight cycles after accomplishing the 
modification, accomplish the following:
    (1) Perform either a high frequency eddy current or dye 
penetrant inspection to detect cracking of the modified actuator rib 
fitting, in accordance with the alert service bulletin.
    (2) Repeat the inspection thereafter at intervals not to exceed 
2,500 flight cycles until the fitting is replaced with a new steel 
rib fitting, in accordance with Part III of the Accomplishment 
Instructions of the alert service bulletin. This replacement 
constitutes terminating action for the requirements of this AD for 
that fitting.
    (f) Replacement of aluminum actuator rib fittings with new steel 
actuator rib fittings in accordance with Part III of the 
Accomplishment Instructions of Boeing Alert Service Bulletin 727-
32A0399, dated July 13, 1995, constitutes terminating action for the 
requirements of this AD.
    (g) An alternative method of compliance or adjustment of the 
compliance time that provides an acceptable level of safety may be 
used if approved by the Manager, Seattle Aircraft Certification 
Office (ACO), FAA, Transport Airplane Directorate. Operators shall 
submit their requests through an appropriate FAA Principal 
Maintenance Inspector, who may add comments and then send it to the 
Manager, Seattle ACO.
    Note 2: Information concerning the existence of approved 
alternative methods of compliance with this AD, if any, may be 
obtained from the Seattle ACO.
    (h) 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.
    (i) The actions shall be done in accordance with Boeing Alert 
Service Bulletin 727-32A0399, dated July 13, 1995. 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 Airplane Group, 
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 Office of the Federal 
Register, 800 North Capitol Street, NW., suite 700, Washington, DC.
    (j) This amendment becomes effective on March 4, 1997.

    Issued in Renton, Washington, on January 14, 1997.
    S.R. Miller,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 97-1440 Filed 1-27-97; 8:45 am]
BILLING CODE 4910-13-U