[Federal Register Volume 64, Number 162 (Monday, August 23, 1999)]
[Rules and Regulations]
[Pages 45870-45872]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 99-21364]
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DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 39
[Docket No. 97-NM-129-AD; Amendment 39-11260; AD 99-17-12]
RIN 2120-AA64
Airworthiness Directives; British Aerospace Model BAe 146 and
Model Avro 146-RJ 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 British Aerospace Model BAe 146 and Model Avro
146-RJ series airplanes, that requires a one-time measurement to
determine the thickness of the outer links of the side stays of the
main landing gear (MLG), and corrective actions, if necessary. This
amendment also provides for replacement of a thin outer link with a new
or serviceable part in lieu of certain follow-on inspections. This
amendment is prompted by issuance of mandatory continuing airworthiness
information by a foreign civil airworthiness authority. The actions
specified by this AD are intended to prevent cracking of the outer
links of the side stays of the MLG, which could result in failure of a
side stay, and consequent collapse of the landing gear.
DATES: Effective September 27, 1999.
The incorporation by reference of certain publications listed in
the regulations is approved by the Director of the Federal Register as
of September 27, 1999.
ADDRESSES: The service information referenced in this AD may be
obtained from AI(R) American Support, Inc., 13850 Mclearen Road,
Herndon, Virginia 20171. 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: Norman B. Martenson, Manager,
International Branch, ANM-116, FAA, Transport Airplane Directorate,
1601 Lind Avenue, SW., Renton, Washington 98055-4056; telephone (425)
227-2110; fax (425) 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 British Aerospace Model
BAe 146 and Model Avro 146-RG series airplanes was published in the
Federal Register on September 8, 1998 (63 FR 47445). That action
proposed to require a one-time measurement to determine the thickness
of the outer links of the side stays of the main landing gear (MLG),
and corrective actions, if necessary. That action also proposed to
provide for replacement of a thin outer link with a new or serviceable
part in lieu of certain follow-on inspections.
Interested persons have been afforded an opportunity to participate
in the making of this amendment. Due consideration has been given to
the comments received.
Request to Allow Flight With Cracks
One commenter, the manufacturer, requests that the proposal be
revised to allow flight with certain specified cracking limits. The
commenter points out that, although the inspection for cracking is
easily accomplished, the replacement of a cracked part is difficult
(necessitates acquisition of the replacement part and takes about 12
hours of elapsed time for the installation). The commenter states that
a side stay with a 1 millimeter (mm) crack in the outer links of the
side stays of the MLG was returned to the commenter, and was then
subjected to fatigue testing by applying 20,000 cycles of the test
spectra, where 1 cycle of test spectra was equivalent to 1 flight. The
crack grew to 30 mm in length. The side stay was then tested to 130
percent and finally to 165 percent of limit load without failure (i.e.,
in excess of ultimate load). The commenter notes that, based on those
fatigue testing results, the United Kingdom Civil Aviation Authority
(CAA) granted approval for continued revenue service with cracking
detected up to 19.05 mm, and required inspections to detect cracking at
intervals of 70 landings, up to a maximum of 500 landings.
The FAA concurs with the commenter's request in this case. Since
the outer link of the main landing gear side stay is readily
inspectable for cracking during the normal operation of the airplane,
the FAA has determined that cracking could be discovered at a remote
site, but that acquiring parts and accomplishing the repair would be
difficult. In addition, the FAA has determined that the commenter has
provided a conservative demonstration that the airplane can retain FAA-
certificated strength requirements for a limited period of time until
the cracked part is replaced. Therefore, continued flight of the
airplane may be permitted when cracking exists that is within the
limits described in the service bulletin, provided that visual
inspections for cracking and eventual replacement of the cracked part
are performed at the times specified in the final rule. The FAA has
revised paragraph (a)(2)(ii)(B) of the final rule and added a new
paragraph (a)(2)(ii)(C) to the final rule that reflect these changes.
Request to Revise the Unsafe Condition
This same commenter notes that while the proposal states that
cracking of the outer links of the side stays of the MLG could ``result
in increased braking distance during landing and consequent runway
overrun,'' the actual unsafe condition is that the cracking could
result in failure of the side stay, which would result in collapse of
the main landing gear.
The FAA infers that the commenter is requesting that the unsafe
condition be revised. The FAA acknowledges that, although the proposal
describes one possible unsafe outcome of a main landing gear collapse,
other unsafe outcomes are possible. The FAA concurs that, in this case,
the commenter's suggested revision is preferable to the proposal's
description in that it is a more precise statement of the actual
consequence of cracking of the outer links of the side stays of the
[[Page 45871]]
MLG. The FAA has revised the final rule to reflect the commenter's
suggestion.
In addition, the FAA has added a new ``Note 4'' to the final rule
to add a definition of the term ``detailed visual inspection.''
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 described
previously. 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 37 Model BAe 146 and Model Avro 146-RJ
series airplanes of U.S. registry will be affected by this AD. It will
take approximately 1 work hour per airplane to accomplish the required
measurement, at an average labor rate of $60 per work hour. Required
parts will be supplied by the manufacturer at no cost to operators.
Based on this figure, the cost impact of the measurement required by
this AD on U.S. operators is estimated to be $2,220, or $60 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.
Sec. 39.13 [Amended]
2. Section 39.13 is amended by adding the following new
airworthiness directive:
99-17-12 British Aerospace Regional Aircraft (Formerly British
Aerospace Regional Aircraft Limited, Avro International Aerospace
Division; British Aerospace, PLC; British Aerospace Commercial
Aircraft Limited): Amendment 39-11260. Docket 97-NM-129-AD.
Applicability: Model BAe 146 and Model Avro 146-RJ series
airplanes, equipped with side stays of the main landing gear (MLG)
having part numbers (P/N) listed in Messier-Dowty Service Bulletin
146-32-128, dated December 6, 1996; certificated in any category.
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 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 cracking of the outer links of the side stays of the
main landing gear (MLG), which could result in failure of a side
stay, and consequent collapse of the landing gear; accomplish the
following:
(a) Within 500 landings or 60 days after the effective date of
this AD, whichever occurs later, perform a one-time measurement to
determine the thickness of the outer links of the side stays of the
MLG, in accordance with British Aerospace Service Bulletin SB.32-
144, dated December 11, 1996.
Note 2: The British Aerospace service bulletin references
Messier-Dowty Service Bulletin 146-32-128, dated December 6, 1996,
as an additional source of service information for accomplishment of
the measurement.
(1) If the profile gauge does not slip over the top edge of the
outer link profile, no further action is required by this AD.
(2) If the profile gauge slips over the top edge of the outer
link profile, prior to further flight, accomplish either paragraph
(a)(2)(i) or (a)(2)(ii) of this AD.
(i) Replace the outer link with a new or serviceable part in
accordance with the service bulletin. After replacement of the outer
link, no further action is required by this AD.
Note 3: For purposes of this AD, a ``serviceable'' outer link is
defined as an outer link that is not cracked and on which a profile
gauge does not slip over the top edge of the profile, as described
in the service bulletin.
(ii) Perform a detailed visual inspection to detect cracking of
the outer links of the side stays of the MLG, in accordance with the
service bulletin.
Note 4: For the purposes of this AD, a detailed visual
inspection is defined as: ``As intensive visual examination of a
specific structural area, system, installation, or assembly to
detect damage, failure, or irregularity. Available lighting is
normally supplemented with a direct source of good lighting at
intensity deemed appropriate by the inspector. Inspection aids such
as mirror, magnifying lenses, etc., may be used. Surface cleaning
and elaborate access procedures may be required.''
(A) If no cracking is detected, repeat the detailed visual
inspection thereafter at intervals not to exceed 4,000 landings.
(B) If any cracking of only one flange of an outer link is
detected, and the cracking is within the limits specified by the
service bulletin: Repeat the detailed visual inspection at intervals
not to exceed 70 landings, and replace the cracked outer link with a
new or serviceable part in accordance with the service bulletin
within 500 landings after the cracking is detected. After
replacement of the outer link, no further action is required by this
AD.
(C) If any cracking of more than one flange of an outer link is
detected, or if any cracking is detected that is outside the limits
specified by the service bulletin: Prior to further flight, replace
the cracked outer link with a new or serviceable part in accordance
with the service bulletin. After replacement of the outer link, no
further action is required by this AD.
(b) As of the effective date of this AD, no person shall install
on any airplane a side stay of the MLG having a part number listed
in paragraph 1.A. of Messier-Dowty Service Bulletin 146-32-128,
dated December 6, 1996; unless the profile gauge does not slip over
the profile of the outer links of the side stay, as described in
British Aerospace Service Bulletin SB.32-144, dated December 11,
1996.
[[Page 45872]]
Alternative Methods of Compliance
(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, International Branch, ANM-116, 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, International
Branch, ANM-116.
Note 5: Information concerning the existence of approved
alternative methods of compliance with this AD, if any, may be
obtained from the International Branch, ANM-116.
Special Flight Permits
(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.
Incorporation by Reference
(e) The actions shall be done in accordance with British
Aerospace Service Bulletin SB.32-144, dated December 11, 1996. 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 AI(R) American Support , Inc., 13850
Mclearen Road, Herndon, Virginia 20171. 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.
Note 6: The subject of this AD is addressed in British
airworthiness directive 005-12-96.
(f) This amendment becomes effective on September 27, 1999.
Issued in Renton, Washington, on August 10, 1999.
D.L. Riggin,
Acting Manager, Transport Airplane Directorate, Aircraft Certification
Service.
[FR Doc. 99-21364 Filed 8-20-99; 8:45 am]
BILLING CODE 4910-13-P
