[Federal Register Volume 59, Number 247 (Tuesday, December 27, 1994)]
[Unknown Section]
[Page 0]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 94-30492]
[[Page Unknown]]
[Federal Register: December 27, 1994]
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DEPARTMENT OF TRANSPORTATION
14 CFR Part 39
[Docket No. 93-NM-205-AD; Amendment 39-9099; AD 94-26-03]
Airworthiness Directives; Fokker Model F28 Mark 1000, 2000, 3000,
and 4000 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 series airplanes, that requires
inspection to detect cracking in the area of the side stay attachment
lugs of the fitting subassembly of the main landing gear (MLG), and
replacement of cracked subassemblies with new or serviceable
subassemblies. This amendment is prompted by reports of cracking in the
subassembly of the MLG. The actions specified by this AD are intended
to prevent damage to and/or failure of the support structure of the
MLG.
DATES: Effective January 26, 1995.
The incorporation by reference of certain publications listed in
the regulations is approved by the Director of the Federal Register as
of January 26, 1995.
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: Mark Quam, Aerospace Engineer,
Standardization Branch, ANM-113, FAA, Transport Airplane Directorate,
1601 Lind Avenue, SW., Renton, Washington 98055-4056; telephone (206)
227-2145; fax (206) 227-1320.
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 F-28 Mark
1000, 2000, 3000, and 4000 series airplanes was published in the
Federal Register on April 5, 1994 (59 FR 15875). That action proposed
to require a one-time inspection to detect cracking in the area of the
side stay attachment lugs of the fitting subassembly of the main
landing gear (MLG), and replacement of cracked subassemblies with new
or serviceable subassemblies.
Interested persons have been afforded an opportunity to participate
in the making of this amendment. Due consideration has been given to
the comments received.
One commenter supports the proposal.
One commenter requests that the proposed rule be withdrawn and that
a supplemental notice be issued that would propose the accomplishment
of a ``refurbishment'' program developed by the commenter. This
commenter indicates that the inspection and rework proposed in the
notice may actually aggravate, rather than prevent, damage to the
subject fitting assemblies. This commenter reports that, within several
days after reworking the lugs in accordance with the method proposed in
the notice, corrosion damage indications reappeared. In order to ensure
that all evidence of corrosion was removed, the commenter had to
accomplish an intensive refurbishment of the main landing gear side
stay attachment lugs. It is this refurbishment process that the
commenter requests to be required by the proposed rule.
The FAA does not agree with the commenter's request. The commenter
did not provide sufficient data to establish that the procedure
required by this rule (namely, a cleaning procedure that is necessary
to remove surface corrosion in order to obtain an adequate eddy current
inspection) contributes to any aggravation of a corrosion condition.
The FAA has determined that the cleaning and eddy current inspection
are sufficient, if no cracks are detected, to allow the main fitting
sub-assembly to remain on the airplane until the next overhaul, when a
thorough inspection, corrosion removal, and corrosion control process
can be accomplished.
This same commenter requests that the proposed AD be revised to
provide ``credit'' for inspections accomplished during overhaul
procedures that were performed prior to the effective date of the final
rule. The commenter points out that Revision 2 of Fokker F28 Service
Experience Digest 32-10, Subject No. 008, states that, if the
inspection and restoration of the protective finish on the subject
assembly are accomplished, as is recommended during the inspections
called out in the referenced service bulletin or during normal
overhaul, no repetitive inspections will be necessary between overhaul
periods. The commenter considers that this implies that the damage to
the anodic film is an isolated occurrence, and that stress corrosion
cracking will not occur if the anodic film is intact when the unit
enters service. The commenter states that, compared to a specialized
shop environment, field inspections and rework operations (as proposed
in the notice) are less likely to ensure that all corrosion is detected
and removed. Further, rework that exposes end grains and increases
stress levels can aggravate, rather than arrest, the propensity for
further corrosion. In this commenter's overhaul shop, corrosion removal
is verified after machining by a process beginning with a chemical etch
treatment that removes the surfaced layer of metal smeared by
machining, followed by a high-sensitivity fluorescent penetrant
inspection.
The FAA concurs in part. Although the Fokker F28 Service Experience
Digest referenced by the commenter does state that accomplishment of
normal overhaul ``will ensure that no repetitive inspections are
required between overhaul periods,'' the overhaul instructions provided
may not be entirely adequate to support that statement. Therefore, the
FAA agrees with the commenter's suggestion to provide credit to
operators for inspections that were accomplished during overhaul prior
to the effective date of the AD, but only provided that:
1. The overhaul was accomplished within the normal overhaul period
(12,000 cycles or 12 years, whichever comes first); and
2. The overhaul was accomplished in accordance with Dowty Aerospace
Landing Gear (DALG) Component Maintenance Manual (CMM), dated September
1977 or later; and
3. Any resulting repairs were accomplished in accordance with the
DALG CMM, dated November 25, 1992, or later; or, if repairs were
accomplished after September 1977 but before November 25, 1992, they
were performed with concurrence (concession) from DALG.
The FAA has revised paragraph (a) of the final rule, to provide
such ``credit'' to operators who have performed this procedure.
One commenter requests that the proposed rule be revised to permit
the installation of uninspected (non-identified) subassemblies after
the effective date of the AD and until the compliance time for
inspection, which is 3 months after the effective date. This commenter
points out that the proposal would require that, as of the effective
date of the final rule, no operator could install any subassembly that
had not been previously inspected and identified in accordance with the
requirements of proposed paragraph (a). The commenter is concerned that
this would not allow the installation of an uninspected serviceable
part during maintenance that was not related to the AD itself. The
commenter states that this does not appear to be consistent with
previous AD's that have dealt with affected parts not installed on an
airplane.
The FAA does not concur with the commenter's request. Neither does
the FAA agree that this is ``not consistent with previous AD's.'' The
FAA has issued numerous AD's over the past years that have called for
the removal of discrepant parts that have been determined to create an
unsafe condition; those AD's normally contain a statement indicating
that none of those discrepant-type parts may be installed on any
airplane in the future. Such statements are necessary in order to
prohibit the installation of spares of the discrepant part. In general,
once an unsafe condition has been determined to exist with regard to a
part, it is the FAA's normal policy not to allow that condition--or
that part--to be re-introduced into the fleet.
Further, in developing the technical information on which every AD
is based, one of the important considerations is the availability of
parts that the AD will require to be installed. When it is determined
that ample numbers of those (safe) parts are immediately available to
operators, it is the FAA's policy to prohibit installation of the
``unsafe'' parts after the effective date of the AD. Removing an unsafe
condition that already exists on an airplane necessarily involves
performing maintenance on the airplane, and the FAA always provides
some kind of ``grace period'' in order to minimize disruption of
operations. On the other hand, prohibiting installation of spares that
have been determined to create an unsafe condition does not require any
additional maintenance activity; it simply requires use of one part
rather than another.
Put in other terms, the purpose of the AD's compliance time is to
give the operators time to get the discrepant parts off the airplane.
The time interval selected takes into account not only safety
implications, but the size of the fleet and convenient maintenance
schedules. However, the compliance time is not meant as a time for
operators to put discrepant parts on the airplane in the meantime.
Further, the FAA considers that the period of time between
publication of the final rule in the Federal Register and the effective
date of the final rule (usually 30 days) is sufficient to provide
operators with an opportunity to determine their immediate need for
modified spares and to obtain them. Of course, in individual cases
where this is not possible, every AD contains a provision that allows
an operator to obtain an extension of compliance time based upon a
specific showing of need.
In light of these issues, the FAA finds that prohibiting
installation of uninspected (non-identified) subassemblies on an
airplane as of the effective date of this final rule does increase
safety and does not impose undue burdens on operators.
As a result of recent communications with the Air Transport
Association (ATA) of America, the FAA has learned that, in general,
some operators may misunderstand the legal effect of AD's on airplanes
that are identified in the applicability provision of the AD, but that
have been altered or repaired in the area addressed by the AD. The FAA
points out that all airplanes identified in the applicability provision
of an AD are legally subject to the AD. If an airplane has been altered
or repaired in the affected area in such a way as to affect compliance
with the AD, the owner or operator is required to obtain FAA approval
for an alternative method of compliance with the AD, in accordance with
the paragraph of each AD that provides for such approvals. A note has
been added to the final rule to clarify this requirement.
The FAA has recently reviewed the figures it has used over the past
several years in calculating the economic impact of AD activity. In
order to account for various inflationary costs in the airline
industry, the FAA has determined that it is necessary to increase the
labor rate used in these calculations from $55 per work hour to $60 per
work hour. The economic impact information, below, has been revised to
reflect this increase in the specified hourly labor rate.
After careful review of the available data, including the comments
above, the FAA has determined that air safety and the public interest
require the adoption of the rule with the changes previously described.
The AA has determined that these changes will neither increase the
economic burden on any operator nor increase the scope of the AD.
The FAA estimates that 42 airplanes of U.S. registry will be
affected by this AD, that it will take approximately 14 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 total cost
impact of the AD on U.S. operators is estimated to be $35,280, or $840
per airplane.
The total 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.
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. 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 adding the following new
airworthiness directive:
94-26-03 Fokker: Amendment 39-9099. Docket 93-NM-205-AD.
Applicability: Model F28 Mark 1000, 2000, 3000, and 4000 series
airplanes, serial numbers 11003 through 11241 inclusive, 11991, and
11992; certificated in any category, and equipped with any of the
following Dowty Aerospace Gloucester main undercarriage unit part
numbers:
200427003/004/005/006/007/008/009/010,
200633001/002/005/006,
200642001/002/003/004/005/006,
200739001/002/003/004,
200752001/002/003/004, or
200782001/002/003/004/005/006/007/008.
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 use the authority
provided in paragraph (d) to request approval from the FAA. This
approval may address either no action, if the current configuration
eliminates the unsafe condition; or different actions necessary to
address the unsafe condition described in this AD. Such a request
should include an assessment of the effect of the changed
configuration on the unsafe condition addressed by this AD. In no
case does the presence of any modification, alteration, or repair
remove any airplane from the applicability of this AD.
Compliance: Required as indicated, unless accomplished
previously.
To prevent damage to and/or failure of the support structure of
the main landing gear (MLG), accomplish the following:
(a) Except as provided by paragraph (b) of this AD: Within 3
months after the effective date of this AD, perform an eddy current
inspection to detect cracking in the area of the side stay
attachment lugs of the fitting subassembly of the MLG in accordance
with Fokker Service Bulletin F28/32-149, dated August 30, 1991. If
any cracked subassembly is found, prior to further flight, replace
it with a new subassembly, or a serviceable subassembly that has
been identified previously with service bulletin number ``32-161R''
on its nameplate, in accordance with Dowty Aerospace Gloucester
Service Bulletin 32-161R, Revision 2, dated January 7, 1992.
(b) In lieu of performing the requirements of paragraph (a) of
this AD, verify that the items specified in paragraphs (b)(1),
(b)(2), and (b)(3) of this AD have been accomplished with respect to
the main undercarriage unit of the MLG on the affected airplane(s).
Operators who verify the accomplishment of all of these items are
considered to be in compliance with the requirements of this AD.
(1) The main landing gear overhaul period has not exceeded
12,000 landings or 12 years, whichever comes first; and
(2) The last overhaul was accomplished in accordance with Dowty
Aerospace Landing Gear (DALG) Component Maintenance Manual (CMM),
dated September 1977 or later; and
(3) Any repairs accomplished during overhaul were accomplished
in accordance with the DALG CMM, dated November 25, 1992 or later;
or any repairs accomplished prior to November 25, 1992, but later
than September 1977, were performed with concurrence (concession)
from DALG.
(c) As of the effective date of this AD, no person shall install
on any airplane a main undercarriage unit, having any of the
following Dowty Aerospace Gloucester part numbers, that has not been
identified previously with service bulletin number ``32-161R'' on
its nameplate, or that has not been verified to have met the items
specified in paragraph (b) of this AD:
200427003/004/005/006/007/008/009/010,
200633001/002/005/006,
200642001/002/003/004/005/006,
200739001/002/003/004,
200752001/002/003/004, or
200782001/002/003/004/005/006/007/008.
(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, 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.
(e) Special flight permits may be issued in accordance with
Secs. 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.
(f) The inspection shall be done in accordance with Fokker
Service Bulletin F28/32-149, dated August 30, 1991. 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.
(g) This amendment becomes effective on January 26, 1995.
Issued in Renton, Washington, on December 12, 1994.
Darrell M. Pederson,
Acting Manager, Transport Airplane Directorate, Aircraft Certification
Service.
[FR Doc. 94-30492 Filed 12-23-94; 8:45 am]
BILLING CODE 4910-13-U