[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