[Federal Register Volume 59, Number 25 (Monday, February 7, 1994)]
[Unknown Section]
[Page 0]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 94-2658]
[[Page Unknown]]
[Federal Register: February 7, 1994]
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DEPARTMENT OF TRANSPORTATION
14 CFR Part 39
[Docket No. 93-NM-194-AD]
Airworthiness Directives; de Havilland, Inc., Model DHC-8-100 and
-300 Series Airplanes
AGENCY: Federal Aviation Administration, DOT.
ACTION: Notice of proposed rulemaking (NPRM).
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SUMMARY: This document proposes the supersedure of an existing
airworthiness directive (AD), applicable to certain de Havilland, Inc.,
Model DHC-8-100 and -300 series airplanes, that currently requires
inspection to detect cracks of the upper drag strut trunnion fittings
of the nose landing gear, inspection to verify tightness of the fitting
attachment bolts, and replacement of the fittings or fasteners, if
necessary. This action would require a terminating modification that
would eliminate the need for repetitive inspections; and would limit
the applicability of the rule. This proposal is prompted by the
development of a modification that positively addresses the identified
unsafe condition. The actions specified by the proposed AD are intended
to prevent failure of the upper drag strut trunnion fittings of the
nose landing gear, which could lead to collapse of the nose landing
gear.
DATES: Comments must be received by April 4, 1994.
ADDRESSES: Submit comments in triplicate to the Federal Aviation
Administration (FAA), Transport Airplane Directorate, ANM-103,
Attention: Rules Docket No. 93-NM-194-AD, 1601 Lind Avenue, SW.,
Renton, Washington 98055-4056. Comments may be inspected at this
location between 9 a.m. and 3 p.m., Monday through Friday, except
Federal holidays.
The service information referenced in the proposed rule may be
obtained from de Havilland, Inc., Garratt Boulevard, Downsview, Ontario
M3K 1Y5, Canada. This information may be examined at the FAA, Transport
Airplane Directorate, 1601 Lind Avenue, SW., Renton, Washington; or at
the FAA, Engine and Propeller Directorate, New York Aircraft
Certification Office, 181 South Franklin Avenue, room 202, Valley
Stream, New York.
FOR FURTHER INFORMATION CONTACT: Jon Hjelm, Aerospace Engineer,
Airframe Branch, ANE-172, FAA, Engine and Propeller Directorate, New
York Aircraft Certification Office, 181 South Franklin Avenue, room
202, Valley Stream, New York 11581; telephone (516) 791-6220; fax (516)
791-9024.
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 93-NM-194-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. 93-NM-194-AD, 1601 Lind Avenue, SW., Renton, Washington
98055-4056.
Discussion
On April 15, 1993, the FAA issued AD 93-08-03, Amendment 39-8550
(58 FR 25549, April 27, 1993), applicable to certain de Havilland Model
DHC-8-100 and -300 series airplanes, to require inspection to detect
cracks of the upper drag strut trunnion fittings of the nose landing
gear, inspection to verify tightness of the fitting attachment bolts,
and replacement of the fittings or fasteners, if necessary. That action
was prompted by reports of cracks detected in two trunnion fittings
which retain and support the nose landing gear upper drag link. Studies
indicate that these fittings have a low fatigue life. Initial
investigations revealed that ground handling caused higher loads than
initially predicted, primarily due to towing of the airplane. Cracked
trunnion fittings may be further aggravated by loose fasteners (loose
nuts, washers, and bolts). The requirements of that AD are intended to
prevent failure of the upper drag strut trunnion fittings of the nose
landing gear, which could lead to collapse of the nose landing gear.
Since issuance of that AD, the manufacturer has designed a
modification of the nose landing gear drag link trunnion fittings and
fasteners that will significantly improve the fatigue life of these
parts and should eliminate the possibility of cracked fittings. De
Havilland has issued Service Bulletin S.B. 8-53-45, dated July 12,
1993, that describes procedures for installation of Modification 8/
1880, which entails replacing both currently-installed upper drag strut
trunnion fittings and fasteners of the nose landing gear with new,
improved upper drag strut trunnion fittings and new fasteners, and
installation of a new sensor bracket. Installation of new fasteners
will secure the fittings. The grease nipple in each new fitting is
installed at an angle to the horizontal to allow easier access for
lubrication. Transport Canada Aviation, which is the airworthiness
authority for Canada, has approved this service bulletin, but it has
not classified it as mandatory.
The FAA has reviewed Modification 8/1880 and has determined that
implementation of this modification will positively address the unsafe
condition identified as failure of the upper drag strut trunnion
fittings of the nose landing gear, which could lead to collapse of the
nose landing gear.
This airplane model is manufactured in Canada and is type
certificated for operation in the United States under the provisions of
Section 21.29 of the Federal Aviation Regulations and the applicable
bilateral airworthiness agreement. Pursuant to this bilateral
airworthiness agreement, Transport Canada Aviation has kept the FAA
informed of the situation described above. The FAA has examined the
findings of Transport Canada Aviation, 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.
Since an unsafe condition has been identified that is likely to
exist or develop on other products of the same type design registered
in the United States, the proposed AD would supersede AD 93-08-03 to
continue to require inspection to detect cracks of the upper drag strut
trunnion fittings of the nose landing gear, inspection to verify
tightness of the fitting attachment bolts, and replacement of the
fittings or fasteners, if necessary. Additionally, the proposed AD
would require incorporation of Modification 8/1880. When accomplished,
this modification would terminate the need for the currently required
inspections. The actions would be required to be accomplished in
accordance with the service bulletin described previously.
Additionally, the proposed AD would limit the applicability of the
rule to exclude those airplanes on which Modification 8/1880 has been
accomplished previously. The manufacturer has installed Modification 8/
1880 on airplanes having serial numbers 385 and subsequent prior to
delivery. Airplanes so modified are not subject to the unsafe condition
addressed by this proposed AD.
The FAA estimates that 125 airplanes of U.S. registry would be
affected by this proposed AD, that it would take approximately 9 work
hours per airplane to accomplish the proposed actions, and that the
average labor rate is $55 per work hour. Required parts would cost
approximately $1,860 per airplane. Based on these figures, the total
cost impact of the proposed AD on U.S. operators is estimated to be
$294,375, or $2,355 per airplane.
The total cost impact figure discussed above is 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.
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 14
CFR part 39 of the Federal Aviation Regulations as follows:
PART 39--AIRWORTHINESS DIRECTIVES
1. The authority citation for part 39 continues to read as follows:
Authority: 49 U.S.C. App. 1354(a), 1421 and 1423; 49 U.S.C.
106(g); and 14 CFR 11.89.
Sec. 39.13 [Amended]
2. Section 39.13 is amended by removing amendment 39-8550 (58 FR
25549, April 27, 1993), and by adding a new airworthiness directive
(AD), to read as follows:
De Havilland, Inc.: Docket 93-NM-194-AD. Supersedes AD 93-08-03,
Amendment 39-8550.
Applicability: Model DHC-8-102, -103, -301, -311, and -314
series airplanes on which Modification 8/1880 (as described in de
Havilland Service Bulletin S.B. 8-53-45, dated July 12, 1993) has
not been accomplished; certificated in any category.
Compliance: Required as indicated, unless accomplished
previously.
To prevent failure of the upper drag strut trunnion fittings of
the nose landing gear, which could lead to collapse of the nose
landing gear, accomplish the following:
(a) Within 500 landings after May 27, 1993 (the effective date
of AD 93-08-03, Amendment 39-8550), unless accomplished within the
last 500 landings, conduct a visual inspection of both upper drag
strut trunnion fittings of the nose landing gear to detect cracks;
and conduct an inspection of the fitting attachment bolts to verify
tightness; in accordance with de Havilland DHC-8 Alert Service
Bulletin S.B. A8-53-40, Revision `A', dated June 12, 1992; or
Revision `B', dated February 24, 1993.
(1) If no crack is detected in the upper drag strut trunnion
fittings of the nose landing gear, and no looseness is detected in
the fitting attachment bolts, repeat the inspections at intervals
not to exceed 1,000 landings until the modification required by
paragraph (b) of this AD is accomplished.
(2) If any crack is detected on either fitting, prior to further
flight, replace both fittings with confirmed crack-free fittings in
accordance with the service bulletin. After such replacement, the
inspections required by this paragraph must continue at intervals
not to exceed 1,000 landings until the modification required by
paragraph (b) of this AD is accomplished.
(3) If any fitting attachment bolt is found to be loose during
the initial inspection, prior to further flight, replace the
fasteners (nut, washer, and bolt) that secure the fitting, in
accordance with the service bulletin. After such replacement, the
inspections required by this paragraph must continue at intervals
not to exceed 1,000 landings until the modification required by
paragraph (b) of this AD is accomplished.
(4) If any fastener is found to be loose during any repetitive
inspection required by this AD, prior to further flight, tighten the
bolt to the value specified in the service bulletin.
(b) Within 6 months after the effective date of this AD, install
Modification 8/1880 (which entails replacing both of the currently-
installed upper drag strut trunnion fittings and fasteners of the
nose landing gear with new, improved upper drag strut trunnion
fittings and new fasteners, and installing a new sensor bracket), in
accordance with de Havilland Service Bulletin S.B. 8-53-45, dated
July 12, 1993. Installation of this modification constitutes
terminating action for the inspection requirements of this AD.
(c) Installation of Modification 8/1880, in accordance with de
Havilland Service Bulletin S.B. 8-53-45, dated July 12, 1993,
constitutes terminating action for the inspections required by this
AD.
(d) 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, New York Aircraft Certification
Office (ACO), ANE-170, FAA, Engine and Propeller Directorate.
Operators shall submit their requests through an appropriate FAA
Principal Maintenance Inspector, who may add comments and then send
it to the Manager, New York ACO.
Note: Information concerning the existence of approved
alternative methods of compliance with this AD, if any, may be
obtained from the New York ACO.
(e) Special flight permits may be issued in accordance with
Federal Aviation Regulations (FAR) 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 February 1, 1994.
Darrell M. Pederson,
Acting Manager, Aircraft Certification Service.
[FR Doc. 94-2658 Filed 2-4-94; 8:45 am]
BILLING CODE 4910-13-U
