[Federal Register Volume 63, Number 222 (Wednesday, November 18, 1998)]
[Rules and Regulations]
[Pages 63975-63977]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 98-30536]
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DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 39
[Docket No. 97-NM-141-AD; Amendment 39-10888; AD 98-24-01]
RIN 2120-AA64
Airworthiness Directives; British Aerospace (Jetstream) Model
4101 Airplanes
AGENCY: Federal Aviation Administration, DOT.
ACTION: Final rule.
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SUMMARY: This amendment adopts a new airworthiness directive (AD),
applicable to certain British Aerospace (Jetstream) Model 4101
airplanes, that requires repetitive detailed visual inspections to
detect cracking or other damage of certain diaphragm support structures
of the forward equipment compartment; and repair, if necessary. This
amendment is prompted by the issuance of mandatory continuing
airworthiness information by a foreign civil airworthiness authority.
The actions specified by this AD are intended to detect and correct
failure of the two diaphragms that support the upper structure of the
forward equipment compartment, which could accelerate fatigue damage in
adjacent structure and result in reduced structural integrity of the
airframe.
DATES: Effective December 23, 1998.
The incorporation by reference of certain publications listed in
the regulations is approved by the Director of the Federal Register as
of December 23, 1998.
ADDRESSES: The service information referenced in this AD may be
obtained from AI(R) American Support, Inc., 13850 Mclearen Road,
Herndon, Virginia 20171. 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: Norman B. Martenson, Manager,
International Branch, ANM-116, FAA, Transport Airplane Directorate,
1601 Lind Avenue, SW., Renton, Washington 98055-4056; telephone (425)
227-2110; fax (425) 227-1149.
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 British Aerospace
(Jetstream) Model 4101 airplanes was published in the Federal Register
on January 8, 1998 (63 FR 1074). That action proposed to require
repetitive detailed visual inspections to detect cracking or other
damage of certain diaphragm support structures of the forward equipment
compartment; and repair, if necessary.
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 Allow Flight With Known Cracks
One commenter, the manufacturer, requests that the proposed AD be
revised to allow operators to continue operation of an unrepaired
airplane for up to 300 flight cycles following detection of cracking of
certain diaphragm support structures of the forward equipment
compartment. The commenter states that, during full-scale fatigue
testing, failure of both diaphragms occurred, and the test continued
for another 24,000 flight cycles before either of the diaphragms was
replaced. The commenter further states that, during the period between
detection of the cracking and replacement of the diaphragms, no damage
was detected that would cause concern regarding the structural
integrity of the airplane. In light of these fatigue testing data, the
commenter notes that the compliance time of 300 flight cycles after
detection of cracking, as specified in the service bulletin, is already
a very conservative threshold.
The FAA does not concur. It is the FAA's policy to require repair
of known cracks prior to further flight, except in certain cases of
unusual need, as discussed below.
This policy is based on the fact that such damaged airplanes do not
conform to the FAA-certificated type design and, therefore, are not
airworthy until a properly approved repair is incorporated. The FAA's
policy regarding flight with known cracks does allow deferral of
repairs in certain cases, if there is an unusual need for a temporary
deferral. Unusual needs include such circumstances as legitimate
difficulty in acquiring parts to accomplish repairs. Because the FAA is
not aware of any unusual need for repair deferral in regard to this AD,
the FAA has determined that any subject diaphragm that is found to be
cracked must be repaired prior to further flight in accordance with a
method approved by the FAA. However, operators may request approval of
an alternative method of compliance if data are
[[Page 63976]]
provided to substantiate that such a method would provide an acceptable
level of safety.
Request To Remove Requirement for Repetitive Inspections After
Repair
One commenter, the manufacturer, requests that the requirement to
continue the repetitive inspections following the installation of an
improved diaphragm be removed from the proposal. The commenter states
that, during full-scale fatigue testing, no new cracking of the
diaphragms was detected following repair of the diaphragms until 65,700
total flight cycles. Based on these data, the commenter states that an
inspection threshold of 20,000 landings after installation of a new
diaphragm, and a repetitive inspection interval thereafter of 6,000
landings, would be adequate to ensure that any cracking would be
detected in a timely manner. The commenter further states that such an
inspection threshold and repetitive interval will be added to the
Airworthiness Limitations specified in Chapter 5 of the Jetstream 4100
Airplane Maintenance Manual (AMM).
The FAA does not concur with the commenter's request to remove the
requirement for repetitive inspections of the diaphragm following
replacement. First, the commenter implies that an improved diaphragm is
available; however, the FAA is not aware of any such improved part.
Further, the lack of specific data in the service bulletin regarding
the repair prevents the FAA from determining whether elimination of the
repetitive inspection requirement is warranted. Also, though the FAA
acknowledges the manufacturer's intent to incorporate a program of
repetitive inspections into the Airworthiness Limitations specified in
Chapter 5 of the AMM, the FAA would have to engage in further
rulemaking in order to require such an inspection program.
Although the FAA does not concur with the request to remove the
repetitive inspection requirement following accomplishment of a repair,
paragraph (b) of this AD contains a provision for requesting approval
of an alternative method of compliance to address operators' unique
circumstances. In accordance with paragraph (b) of this AD, an operator
may submit a repair method, along with a proposed repetitive inspection
program or data to support elimination of the repetitive inspection
requirement, for consideration by the FAA. 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.
Interim Action
This is considered to be interim action until final action is
identified, at which time the FAA may consider further rulemaking.
Cost Impact
The FAA estimates that 55 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 $60 per work hour. Based on these figures, the cost
impact of the AD on U.S. operators is estimated to be $3,300, or $60
per airplane, per inspection cycle.
The cost impact figure discussed above is 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.
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 adding the following new
airworthiness directive:
98-24-01 British Aerospace Regional Aircraft [Formerly Jetstream
Aircraft Limited British Aerospace (Commercial Aircraft) Limited]:
Amendment 39-10888. Docket 97-NM-141-AD.
Applicability: Jetstream Model 4101 airplanes, constructors
numbers 41004 through 41098 inclusive; 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 (b) 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 failure of the two diaphragms that support
the upper structure of the forward equipment compartment, which
could accelerate fatigue damage in adjacent structure and result in
reduced structural integrity of the airframe, accomplish the
following:
(a) Prior to the accumulation of 4,500 total landings, or within
300 landings after the effective date of this AD, whichever occurs
later: Perform a detailed visual inspection to detect cracking or
other damage of the diaphragms installed between station 4 and
station 8 of the forward fuselage, in accordance with Jetstream
Alert Service Bulletin J41-A53-023, dated December 2, 1996.
(1) If no cracking or other damage is detected, repeat the
inspection thereafter at intervals not to exceed 3,000 landings.
(2) If any cracking or other damage is detected, prior to
further flight, repair the diaphragm in accordance with a method
approved by the Manager, International Branch, ANM-116, FAA,
Transport Airplane Directorate. Thereafter, repeat the inspection at
intervals not to exceed 3,000 landings.
(b) 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,
[[Page 63977]]
International Branch, ANM-116. Operators shall submit their requests
through an appropriate FAA Principal Maintenance Inspector, who may
add comments and then send it to the Manager, International Branch,
ANM-116.
Note 2: Information concerning the existence of approved
alternative methods of compliance with this AD, if any, may be
obtained from the International Branch, ANM-116.
(c) 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.
(d) The inspections shall be done in accordance with Jetstream
Alert Service Bulletin J41-A53-023, dated December 2, 1996. 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 AI(R) American Support, Inc., 13850
Mclearen Road, Herndon, Virginia 20171. 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.
Note 3: The subject of this AD is addressed in British
airworthiness directive 007-12-96.
(e) This amendment becomes effective on December 23, 1998.
Issued in Renton, Washington, on November 9, 1998.
Darrell M. Pederson,
Acting Manager, Transport Airplane Directorate, Aircraft Certification
Service.
[FR Doc. 98-30536 Filed 11-17-98; 8:45 am]
BILLING CODE 4910-13-P
