[Federal Register Volume 62, Number 111 (Tuesday, June 10, 1997)]
[Proposed Rules]
[Pages 31536-31538]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 97-15061]
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DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 39
[Docket No. 96-NM-176-AD]
RIN 2120-AA64
Airworthiness Directives; Fokker Model F28 Mark 1000 Through 4000
Series Airplanes
AGENCY: Federal Aviation Administration, DOT.
ACTION: Notice of proposed rulemaking (NPRM).
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SUMMARY: This document proposes the adoption of a new airworthiness
directive (AD) that is applicable to certain Fokker Model F28 Mark 1000
through 4000 series airplanes. This proposal would require replacing
certain flexible hydraulic hoses that connect to the UP-port of the
actuator of each main landing gear (MLG) with certain new flexible
hoses that have built-in restrictor check-valves. This proposal is
prompted by results of tests, which indicate that, for airplanes on
which restrictor check-valves are not installed, sudden movement of the
actuator of the MLG, which could occur under extreme inward sideload
conditions (such as touching down at a large crab angle), may
pressurize the downlock-actuator and lift the MLG toggle-links. The
actions specified by the proposed AD are intended to prevent such
pressurization of the downlock-actuator and consequent lifting of the
toggle-links, which could result in collapse of the MLG and reduced
controllability of the airplane during landing.
DATES: Comments must be received by July 21, 1997.
ADDRESSES: Submit comments in triplicate to the Federal Aviation
Administration (FAA), Transport Airplane Directorate, ANM-103,
Attention: Rules Docket No. 96-NM-176-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 Fokker Aircraft USA, Inc., 1199 North Fairfax Street,
Alexandria, Virginia 22314. This information may be examined at the
FAA, Transport Airplane Directorate, 1601 Lind Avenue, SW., Renton,
Washington.
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 (425)
227-2141; fax (425) 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-176-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-176-AD, 1601 Lind Avenue, SW., Renton, Washington
98055-4056.
Discussion
On August 5, 1996, the FAA issued AD 96-16-05, amendment 39-9706,
(61 FR 40510, August 5, 1996), applicable to certain Fokker Model F28
Mark 1000, 2000, 3000, and 4000 series airplanes, and Model F28 Mark
0100 series airplanes. That AD currently requires repetitive pre-load
adjustments of the downlock-actuator of the main landing gear (MLG),
and also provides for optional terminating action for the repetitive
adjustments. These actions were prompted by a report indicating that,
upon landing, the MLG of a Model F28 Mark 0100 series 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
requirements of that AD are intended to prevent collapse of the MLG,
which could adversely affect the controllability of the airplane during
landing.
Prior to the issuance of AD 96-16-05, the Rijksluchtvaartdienst
(RLD), which is the airworthiness authority for the Netherlands,
notified the FAA that additional mandatory actions are necessary on
certain Fokker Model F28 Mark 1000 through 4000 series airplanes to
correct this unsafe condition because these earlier airplane models do
not have restrictor check-valves. The RLD advises that Fokker has
conducted additional tests of the actuator of the MLG. The results of
these tests revealed that, in addition to pre-load adjustments of the
downlock-actuator of the MLG (as required by AD 96-16-05), installation
of a restrictor check-valve is necessary to address the identified
unsafe condition.
If restrictor check-valves are not installed, sudden movement of
the actuator of the MLG could pressurize the downlock-actuator and lift
the
[[Page 31537]]
toggle-links of the MLG. This situation could occur under extreme side
load conditions, such as touching down at relatively large crab angles,
and could result in collapse of the MLG and reduced controllability of
the airplane during landing.
Because Fokker Model F28 Mark 0100 series airplanes are equipped
with a restrictor check-valve, they are not subject to the requirements
of this proposed AD.
Explanation of Relevant Service Information
Fokker has issued Service Bulletin F28/32-123, Revision 1, dated
June 30, 1994, which describes procedures for replacing certain
flexible hydraulic hoses that connect to the UP-port of the actuator of
the MLG with new flexible hoses that have built-in restrictor check-
valves. The RLD classified this service bulletin as mandatory and
issued Dutch airworthiness directive BLA 94-095 (A), dated July 15,
1994, in order to assure the continued airworthiness of these airplanes
in the Netherlands.
FAA's Conclusions
These airplane models are manufactured in the Netherlands and are
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 RLD has kept the FAA
informed of the situation described above. The FAA has examined the
findings of the RLD, 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 replacing certain
flexible hydraulic hoses that connect to the UP-port of the actuator of
the MLG with certain new flexible hoses that have built-in restrictor
check-valves. These actions would be required to be accomplished in
accordance with the service bulletin described previously.
Cost Impact
The FAA estimates that 37 Fokker Model F28 Mark 1000 through 4000
series airplanes of U.S. registry would be affected by this proposed
AD, that it would take approximately 4 work hours per airplane to
accomplish the proposed actions, and that the average labor rate is $60
per work hour. Required parts would cost approximately $3,554 per
airplane. Based on these figures, the cost impact of the proposed AD on
U.S. operators is estimated to be $140,378, or $3,794 per airplane.
The 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.
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:
Fokker: Docket 96-NM-176-AD.
Applicability: Fokker Model F28 Mark 1000 through 4000 series
airplanes, equipped with flexible hydraulic hoses, part number (P/N)
A71462-401; 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 (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 prevent pressurization of the downlock-actuator during
extreme inward sideload conditions (such as touching down at a large
crab angle) and consequent lifting of the toggle-links of the main
landing gear (MLG), which could result in the collapse of the MLG
and reduced controllability of the airplane during landing,
accomplish the following:
(a) Within 12 months after the effective date of this AD,
replace the flexible hydraulic hoses, P/N A71462-401, that connect
to the UP-port of the actuator of the MLG with new flexible hoses,
P/N 97867-1, that have built-in restrictor check-valves, in
accordance with Fokker Service Bulletin F28/32-123, Revision 1,
dated June 30, 1994.
(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, 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.
(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.
[[Page 31538]]
Issued in Renton, Washington, on June 4, 1997.
Darrell M. Pederson,
Acting Manager, Transport Airplane Directorate, Aircraft Certification
Service.
[FR Doc. 97-15061 Filed 6-9-97; 8:45 am]
BILLING CODE 4910-13-U
