[Federal Register Volume 61, Number 151 (Monday, August 5, 1996)]
[Rules and Regulations]
[Pages 40511-40513]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 96-19523]
[[Page 40511]]
DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 39
[Docket No. 95-NM-87-AD; Amendment 39-9706; AD 96-16-05]
RIN 2120-AA64
Airworthiness Directives; Fokker Model F28 Mark 1000, 2000, 3000,
and 4000 Series Airplanes, and Model F28 Mark 0100 Series 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 Fokker Model F28 Mark 1000, 2000, 3000, and 4000
series airplanes, and Model F28 Mark 0100 series airplanes, that
requires repetitive pre-load adjustments of the main landing gear (MLG)
downlock-actuator. This AD also provides optional terminating action
for the repetitive adjustments. This amendment is prompted by a report
that, upon landing, the MLG of an airplane collapsed as a result of the
lock toggle-links being pulled out of the over-center position by the
downlock-actuator, which was due to the relative movement of the upper
and lower side-stay members. The actions specified by this AD are
intended to prevent collapse of the MLG, which could adversely affect
the controllability of the airplane during landing.
DATES: Effective September 9, 1996.
-The incorporation by reference of certain publications listed in
the regulations is approved by the Director of the Federal Register as
of September 9, 1996.
ADDRESSES: The service information referenced in this AD may be
obtained from Fokker Aircraft USA, Inc., 1199 North Fairfax Street,
Alexandria, Virginia 22314. 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: Tim Dulin, Aerospace Engineer,
Standardization Branch, ANM-113, FAA, Transport Airplane Directorate,
1601 Lind Avenue, SW., Renton, Washington 98055-4056; telephone (206)
227-2141; fax (206) 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 Fokker Model F28 Mark
1000, 2000, 3000, and 4000 series airplanes, and Model F28 Mark 0100
series airplanes was published in the Federal Register on October 16,
1996 (60 FR 53552). That action proposed to require repetitive pre-load
adjustments of the main landing gear (MLG) downlock-actuator.
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.
Support for the Proposal
-One commenter concurs with the proposed rule.
Request to Clarify the Description of Cause of the Unsafe Condition
-One commenter, the airframe manufacturer, requests that the
description of the unsafe condition be clarified. This commenter states
that collapse of the MLG has only occurred under extreme inward side-
load conditions, which are beyond the design ultimate load for landing
conditions. The commenter asserts that the proposed wording of the
unsafe condition suggests that the downlock-actuator itself removed the
over- center position. The commenter further states that the
investigation of the collapse of the MLG showed that the bottomed
downlock-actuator was only an intermediate which transferred the
relative movement between the upper and lower side stay to the lock
toggle links. The commenter suggests that the wording of the unsafe
condition [that appears prior to paragraph (a) of the AD] be revised as
follows: To prevent the collapse of the main landing gear (MLG) under
extreme inward side-load conditions (such as touching down at large
``crab'' angles), due to a lock toggle-link being pulled out of its
over-center position by a bottomed MLG downlock-actuator, as a result
of the relative movement of the upper and lower side stay members * *
*.''
The FAA concurs that clarification is necessary and has revised the
final rule accordingly.
Request to Extend the Compliance Time
-One commenter requests that the compliance time be extended to
allow the inspection within 12 months after the effective date of the
AD, rather than 8 months as proposed. This will allow the inspection to
be accomplished during regularly scheduled maintenance. The commenter
states that the adoption of the proposed compliance time of 8 months
would require operators to schedule special times for the
accomplishment of this inspection at considerable expense beyond what
was estimated in the cost impact of the proposed rule.
-The FAA does not concur. In establishing the compliance times, the
FAA considered not only the degree of urgency associated with the
unsafe condition, but the manufacturer's recommended compliance time
specified in the applicable service bulletins, and the foreign
airworthiness authority's recommended compliance time of 8 months. In
light of these factors, the FAA finds that a compliance time of 8
months is appropriate and should fall during a time of scheduled
maintenance for the majority of affected operators. Paragraph (c) of
the final rule, however, does provide affected operators with the
opportunity to apply for an adjustment of the compliance time if data
are presented to the FAA to justify such an adjustment.
Request to Delete Requirements for Repetitive Adjustments
-One commenter points out that, since paragraph (a) of the proposed
rule does not allow for a terminating action, the proposed rule would
require operators to continue to record accomplishment of the AD
requirements each time the adjustment is performed. This commenter
contends that repetitive requirements in the AD are not necessary,
since operators will revise their maintenance programs to include these
repetitive pre-load adjustment requirements.
-The FAA does not concur that the repetitive adjustment
requirements should be deleted from the AD. However, the FAA has
determined that incorporation of the repetitive adjustments into the
FAA-approved maintenance program is an acceptable alternative method of
compliance with this requirement. This alternative procedure will allow
operators the option to choose either to conduct the repetitive
adjustments in accordance with the AD, or to incorporate the
requirement for repetitive adjustments into the their FAA-approved
maintenance programs. The FAA has added a new paragraph (b) to the
final rule to provide for this alternative.
Request to Revise Wording of Requirement for Repetitive Adjustments
-One commenter requests that the last sentence of paragraph (a) of
the proposed rule be either clarified or
[[Page 40512]]
deleted. That sentence would require repetitive pre-load adjustment of
the MLG downlock-actuator at each scheduled maintenance, installation,
or replacement of the MLG downlock-actuator. The commenter states that
the term ``scheduled maintenance'' could include maintenance (such as
for lubrication only) when a pre-load adjustment is not required.
Additionally, this commenter points out that use of the word
``scheduled'' in this context also is incorrect, since the adjustment
procedure is necessary any time an actuator is installed, regardless of
whether the action is scheduled or unscheduled.
-The FAA concurs and has deleted the words ``scheduled
maintenance'' from paragraph (a) of the final rule.
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
-The FAA estimates that 162 airplanes of U.S. registry will be
affected by this AD, that it will take approximately 8 work hours per
airplane to accomplish the required actions, 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 $77,760, or $480 per
airplane.
-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.
39.13 [Amended]
-2. Section 39.13 is amended by adding the following new
airworthiness directive:
96-16-05 Fokker: Amendment 39-9706. Docket 95-NM-87-AD.
-Applicability: Applies to the airplanes specified in Table 1 of
this AD (equipped as specified), certificated in any category:
Table 1
------------------------------------------------------------------------
Airplane model Equipped with
------------------------------------------------------------------------
F28 Mark 1000, 2000, 3000, Dowty Aerospace main landing gear (MLG)
and 4000 series airplanes. downlock-actuators, part number (P/N)
200497-004 or P/N 200498-004 (on which
Dowty Service Bulletin 32-17 has not
been accomplished)
or
Dowty Aerospace main landing gear (MLG)
downlock-actuators, P/N 200497-005 or
200498-005 (on which Dowty Service
Bulletin 32-17 has been accomplished);
F28 Mark 0100 series Dowty Aerospace MLG downlock-actuators, P/
airplanes. N 201218-005, -006, -007, or -008.
------------------------------------------------------------------------
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) 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 the collapse of the main landing gear (MLG) under
extreme inward side-load conditions (such as touching down at large
``crab'' angles) due to a lock toggle-link being pulled out of its
over-center position by a bottomed MLG downlock-actuator (as a
result of the relative movement of the upper and lower side stay
members), accomplish the following:
(a) Within 8 months after the effective date of this AD, perform
a pre-load adjustment of the MLG downlock-actuator, in accordance
with Fokker Service Bulletin SBF100-32-094, dated November 10, 1994,
or Revision 1, dated March 15, 1995 (for Model F28 Mark 0100 series
airplanes); or Fokker Service Bulletin F28/32-153, dated November
10, 1994 (for Model F28 Mark 1000, 2000, 3000, and 4000 series
airplanes); as applicable. Except as provided by paragraph (b) of
this AD, repeat the adjustment thereafter at each installation or
replacement of the MLG downlock-actuator.
(b) As an alternative to the repetitive adjustment requirements
of paragraph (a) of this AD: Following the accomplishment of the
initial pre-load adjustment of the MLG downlock-actuator required by
paragraph (a) of this AD, incorporate into the FAA-approved
maintenance program provisions for pre-load adjustment procedures of
the MLG downlock-actuator, as described in the F28 Airplane
Maintenance Manual (AMM), Temporary Revision dated November 1994, or
F100 AMM Revision, dated September 1994.
(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,
[[Page 40513]]
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 2: 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.
(e) The adjustment shall be done in accordance with Fokker
Service Bulletin SBF100-32-094, dated November 10, 1994; or Fokker
Service Bulletin SBF100-32-094, Revision 1, dated March 15, 1995; or
Fokker Service Bulletin F28/32-153, dated November 10, 1994; as
applicable. 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 Fokker Aircraft USA,
Inc., 1199 North Fairfax Street, Alexandria, Virginia 22314. 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.
(f) This amendment becomes effective on September 9, 1996.
Issued in Renton, Washington, on July 25, 1996.
Darrell M. Pederson,
Acting Manager, Transport Airplane Directorate, Aircraft Certification
Service.
[FR Doc. 96-19523 Filed 8-2 -96; 8:45 am]
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