[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