[Federal Register Volume 61, Number 219 (Tuesday, November 12, 1996)]
[Proposed Rules]
[Pages 58016-58018]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 96-28868]
-----------------------------------------------------------------------
DEPARTMENT OF TRANSPORTATION
14 CFR Part 39
[Docket No. 96-NM-86-AD]
RIN 2120-AA64
Airworthiness Directives; Jetstream Model 4101 Airplanes
AGENCY: Federal Aviation Administration, DOT.
ACTION: Notice of proposed rulemaking (NPRM).
-----------------------------------------------------------------------
SUMMARY: This document proposes the adoption of a new airworthiness
directive (AD) that is applicable to certain Jetstream Model 4101
airplanes. This proposal would require repetitive inspections to detect
cracking of the offset lightening hole on the drag brace of the left
and right main landing gear (MLG); and replacement of these braces with
braces having a centralized lightening hole. This replacement
terminates the repetitive inspections. This proposal is prompted by a
report indicating that fatigue cracking was detected on the upper link
of a drag brace. The actions specified by the proposed AD are intended
to prevent fatigue cracking of the drag braces of the MLG, which, if
not corrected, could cause the MLG to fail and consequent reduced
controllability of the airplane during takeoff, landing, and taxiing.
DATES: Comments must be received by December 23, 1996.
ADDRESSES: Submit comments in triplicate to the Federal Aviation
Administration (FAA), Transport Airplane Directorate, ANM-103,
Attention: Rules Docket No. 96-NM-86-AD, 1601 Lind Avenue, SW., Renton,
Washington 98055-4056. Comments may be inspected at this location
between 9:00 a.m. and 3:00 p.m., Monday through Friday, except Federal
holidays.
The service information referenced in the proposed rule may be
obtained from Jetstream Aircraft, Inc., P.O. Box 16029, Dulles
International Airport, Washington, DC 20041-6029. This information may
be examined at the FAA, Transport Airplane Directorate, 1601 Lind
Avenue, SW., Renton, Washington.
FOR FURTHER INFORMATION CONTACT: William Schroeder, Aerospace Engineer,
Standardization Branch, ANM-113, FAA, Transport Airplane Directorate,
1601 Lind Avenue, SW., Renton, Washington 98055-4056; telephone (206)
227-2148; fax (206) 227-1149.
SUPPLEMENTARY INFORMATION:
Comments Invited
Interested persons are invited to participate in the making of the
proposed rule by submitting such written data, views, or arguments as
they may desire. Communications shall identify the Rules Docket number
and be submitted in triplicate to the address specified above. All
communications received on or before the closing date for comments,
specified above, will be considered before taking action on the
proposed rule. The proposals contained in this notice may be changed in
light of the comments received.
Comments are specifically invited on the overall regulatory,
economic, environmental, and energy aspects of the proposed rule. All
comments submitted will be available, both before and after the closing
date for comments, in the Rules Docket for examination by interested
persons. A report summarizing each FAA-public contact concerned with
the substance of this proposal will be filed in the Rules Docket.
Commenters wishing the FAA to acknowledge receipt of their comments
submitted in response to this notice must submit a self-addressed,
stamped postcard on which the following statement is made: ``Comments
to Docket Number 96-NM-86-AD.'' The postcard will be date stamped and
returned to the commenter.
Availability of NPRMs
Any person may obtain a copy of this NPRM by submitting a request
to the FAA, Transport Airplane Directorate, ANM-103, Attention: Rules
Docket No. 96-NM-86-AD, 1601 Lind Avenue, SW., Renton, Washington
98055-4056.
Discussion
The Civil Aviation Authority (CAA), which is the airworthiness
authority for
[[Page 58017]]
the United Kingdom, recently notified the FAA that an unsafe condition
may exist on certain Jetstream Model 4101 airplanes. The CAA advises
that it has received a report indicating that cracking has been
detected on the upper link of a drag brace on the main landing gear
(MLG) of a Model 4101 airplane; this cracking was found adjacent to an
offset lightening hole. The cause of the cracking has been attributed
to fatigue. Such fatigue cracking, if not detected and corrected in a
timely manner, could result in failure of the MLG and consequent
reduced controllability of the airplane during takeoff, landing, and
taxiing.
Explanation of Relevant Service Information
Jetstream has issued Service Bulletin J41-32-049, Revision 1, dated
January 15, 1996, which describes procedures for conducting repetitive
visual inspections to detect cracking of the offset lightening hole on
the drag brace of the left and right MLG. The service bulletin
recommends, prior to further flight, the replacement of any cracked
drag brace with a brace having a centralized lightening hole. This
service bulletin also describes procedures for replacing these drag
braces with drag braces that have a centralized lightening hole.
Installation of a drag brace with a centralized lightening hole
eliminates the need for the repetitive inspections. The CAA classified
this service bulletin as mandatory and issued British airworthiness
directive 008-11-95, dated December 29, 1995, in order to assure the
continued airworthiness of these airplanes in the United Kingdom.
FAA's Conclusions
This airplane model is manufactured in the United Kingdom and is
type certificated for operation in the United States under the
provisions of section 21.29 of the Federal Aviation Regulations (14 CFR
21.29) and the applicable bilateral airworthiness agreement. Pursuant
to this bilateral airworthiness agreement, the CAA has kept the FAA
informed of the situation described above. The FAA has examined the
findings of the CAA, reviewed all available information, and determined
that AD action is necessary for products of this type design that are
certificated for operation in the United States.
Explanation of Requirements of Proposed Rule
Since an unsafe condition has been identified that is likely to
exist or develop on other airplanes of the same type design registered
in the United States, the proposed AD would require repetitive detailed
visual inspections of the offset lightening hole on the drag brace of
the left and right MLG to detect cracking. It would also require, prior
to further flight, the replacement of any cracked brace with a brace
having a centralized lightening hole. Such replacement would constitute
terminating action for the repetitive detailed visual inspections. The
actions would be required to be accomplished in accordance with the
service bulletin described previously.
Differences between the Proposed Rule and the CAA Airworthiness
Directive
Operators should note that the proposed AD would require all drag
braces that are the subject to the inspections required by this AD to
be replaced within two years with braces having a centralized
lightening hole. This action would be considered final, terminating
action for this proposed AD. The CAA, however, has not mandated a
similar replacement of the drag braces.
The FAA has determined that long-term continued operational safety
will be better assured by modifications or design changes to remove the
source of the problem, rather than by repetitive inspections. Long term
inspections may not be providing the degree of safety assurance
necessary for the transport airplane fleet. This, coupled with a better
understanding of the human factors associated with numerous repetitive
inspections, has led the FAA to consider placing less emphasis on
special procedures and more emphasis on design improvements. The
proposed replacement requirement is in consonance with these
considerations.
Cost Impact
The FAA estimates that 1 Jetstream Model 4101 airplane of U.S.
registry would be affected by this proposed AD.
It would take approximately 1 work hour per airplane to accomplish
the proposed inspection, at an average labor rate of $60 per work hour.
Based on these figures, the cost impact of the proposed inspection on
the single U.S. operator is estimated to be $60 per inspection cycle.
It would take approximately 2 work hours per airplane to accomplish
the proposed replacement, at an average labor rate of $60 per work
hour. Required parts would be provided by the manufacturer at no cost
to the operator. Based on these figures, the cost impact of the
proposed replacement on the single U.S. operator is estimated to be
$120.
The cost impact figures discussed above are based on assumptions
that no operator has yet accomplished any of the proposed 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 proposed herein would 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
proposal would not have sufficient federalism implications to warrant
the preparation of a Federalism Assessment.
For the reasons discussed above, I certify that this proposed
regulation (1) is not a ``significant regulatory action'' under
Executive Order 12866; (2) is not a ``significant rule'' under the DOT
Regulatory Policies and Procedures (44 FR 11034, February 26, 1979);
and (3) if promulgated, 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 copy of the draft
regulatory evaluation prepared for this action is contained in the
Rules Docket. A copy of it may be obtained by contacting the Rules
Docket at the location provided under the caption ADDRESSES.
List of Subjects in 14 CFR Part 39
Air transportation, Aircraft, Aviation safety, Safety.
The Proposed Amendment
Accordingly, pursuant to the authority delegated to me by the
Administrator, the Federal Aviation Administration proposes to amend
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:
Jetstream Aircraft Limited: Docket 96-NM-86-AD.
Applicability: Model 4101 airplanes having constructors numbers
41004 through 41009 inclusive, and 41017; equipped with a main
landing gear (MLG) on which drag braces having Jetstream part
numbers (P/N) AIR84352-0 through AIR84352-4, inclusive,
[[Page 58018]]
and having offset lightening holes, are installed; certificated in
any category.
Note 1: Drag braces having Jetstream part numbers (P/N)
AIR84352-0 through AIR84352-4 inclusive, can have either offset or
centralized lightening holes. This AD applies only to those
airplanes equipped with those drag braces that have the offset
lightening holes.
Note 2: 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) 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 fatigue cracking of the drag brace of the left and
right MLG which, if not corrected, could cause the MLG to fail and
consequent reduced controllability of the airplane during takeoff,
landing, and taxiing, accomplish the following:
(a) Within 50 hours time-in-service after the effective date of
this AD, perform a detailed visual inspection to detect cracking at
the offset lightening hole on the drag brace of the left and right
MLG, in accordance with Part 1 of Jetstream Service Bulletin J41-32-
049, Revision 1, dated January 15, 1996.
Note 3: Accomplishment of the visual inspection in accordance
with Part 1 of Jetstream Service Bulletin J41-32-049, dated November
21, 1995, is considered acceptable for compliance with this
paragraph.
(1) If no cracking is detected, repeat this inspection
thereafter at intervals not to exceed 50 hours time-in-service until
the requirements of paragraph (b) of this AD have been accomplished.
(2) If any cracking is detected, prior to further flight,
replace the drag brace with a drag brace that has Jetstream part
number (P/N) AIR84352-4 and a centralized lightening hole, in
accordance with Part 2 of Jetstream Service Bulletin J41-32-049,
Revision 1, dated January 15, 1996. This replacement constitutes
terminating action for the repetitive inspections and replacement of
that brace required by paragraphs (a) and (b), respectively, of this
AD.
Note 4: Accomplishment of the replacement in accordance with
Part 2 of Jetstream Service Bulletin J41-32-049, dated November 21,
1995, is considered acceptable for compliance with paragraphs (a)(2)
and (b) of this AD.
(b) Within two years after the effective date of this AD,
replace any MLG drag brace that has P/N AIR84352-0 through AIR84352-
4, inclusive, and an offset lightening hole, with a drag brace that
has Jetstream P/N AIR84352-4 and a centralized lightening hole, in
accordance with Part 2 of Jetstream Service Bulletin J41-32-049,
Revision 1, dated January 15, 1996. This replacement constitutes
terminating action for the repetitive inspections required by
paragraph (a) of this AD.
(c) 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, Standardization Branch, ANM-113,
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,
Standardization Branch, ANM-113.
Note 5: Information concerning the existence of approved
alternative methods of compliance with this AD, if any, may be
obtained from the Standardization Branch, ANM-113.
(d) 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. Issued in Renton,
Washington, on November 5, 1996.
Darrell M. Pederson,
Acting Manager, Transport Airplane Directorate, Aircraft Certification
Service.
[FR Doc. 96-28868 Filed 11-8-96; 8:45 am]
BILLING CODE 4910-13-P
