[Federal Register Volume 61, Number 146 (Monday, July 29, 1996)]
[Proposed Rules]
[Pages 39364-39366]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 96-19150]


      
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 Proposed Rules
                                                 Federal Register
 ________________________________________________________________________
 
 This section of the FEDERAL REGISTER contains notices to the public of 
 the proposed issuance of rules and regulations. The purpose of these 
 notices is to give interested persons an opportunity to participate in 
 the rule making prior to the adoption of the final rules.
 
 ========================================================================
 

  Federal Register / Vol. 61, No. 146 / Monday, July 29, 1996 / 
Proposed Rules  

[[Page 39364]]



DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 96-NM-09-AD]
RIN 2120-AA64


Airworthiness Directives; Shorts Model SD3-60 and SD3-SHERPA 
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 Shorts Model SD3-60 and 
SD3-SHERPA series airplanes. This proposal would require a one-time 
inspection to detect cracks and/or corrosion of the gland nut on the 
shock absorber of the main landing gear (MLG), and follow-on actions. 
The proposal also would require repair or replacement of any cracked/
corroded gland nut with a new nut. This proposal is prompted by a 
report that, due to stress corrosion and cracking of the gland nut on 
the shock absorber, the MLG collapsed on an in-service airplane. The 
actions specified by the proposed AD are intended to prevent such 
stress corrosion or cracking and consequent reduced structural 
integrity of the gland nut, which could result in separation of the 
shock absorber cylinder from the MLG shock absorber body and, 
consequently, lead to the collapse of the MLG during landing.

DATES: Comments must be received by September 9, 1996.

ADDRESSES: Submit comments in triplicate to the Federal Aviation 
Administration (FAA), Transport Airplane Directorate, ANM-103, 
Attention: Rules Docket No. 96-NM-09-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 Short Brothers PLC, 2011 Crystal Drive, Suite 713, 
Arlington, Virginia 22202-3719. This information may be examined at the 
FAA, Transport Airplane Directorate, 1601 Lind Avenue, SW., Renton, 
Washington.

FOR FURTHER INFORMATION CONTACT: Phil Forde, Aerospace Engineer, 
Standardization Branch, ANM-113, FAA, Transport Airplane Directorate, 
1601 Lind Avenue, SW., Renton, Washington 98055-4056; telephone (206) 
227-2146; fax (206) 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-09-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-09-AD, 1601 Lind Avenue, SW., Renton, Washington 
98055-4056.

Discussion -

    The Civil Aviation Authority (CAA), which is the airworthiness 
authority for the United Kingdom, recently notified the FAA that an 
unsafe condition may exist on certain Shorts Model SD3-60 and Model 
SD3-SHERPA series airplanes. The CAA advises that it has received a 
report indicating that the right-hand main landing gear (MLG) collapsed 
on a Model SD3-60 series airplane. The cause of this failure has been 
attributed to stress corrosion and cracking around the inner shoulder 
radius of the gland nut on the shock absorber of the MLG. The effects 
of such stress corrosion and cracking could lead to reduced structural 
integrity of the gland nut. This condition, if not detected and 
corrected in a timely manner, could result in separation of the shock 
absorber cylinder from the MLG shock absorber body and, consequently, 
lead to the collapse of the MLG during landing. -
    The gland nut on the shock absorber of the MLG on certain Model 
SD3-SHERPA series airplanes is identical to that on the affected Model 
SD3-60 series airplanes. Therefore, Model SD3-SHERPA series airplanes 
may be subject to the same unsafe condition revealed on Model SD3-60 
series airplanes.

Explanation of Relevant Service Information -

    Shorts has issued Service Bulletin SD360-32-34 (for Model SD3-60 
series airplanes), and Service Bulletin SD3 SHERPA-32-2 (for Model SD3-
SHERPA series airplanes), both dated September 22, 1995. These service 
bulletins describe procedures for a one-time visual and fluorescent dye 
penetrant inspection to detect cracks and/or corrosion of the gland nut 
on the shock absorber of the MLG, and repair or replacement of the 
gland nut with a new nut, if necessary. Following accomplishment of the 
inspection, these service bulletins also describe procedures for 
applying grease to the threads of the cylinder and applying sealant to 
the inner radius of the gland nut; these procedures will prevent stress 
corrosion and cracking of the subject gland nut. The CAA classified 
these service bulletins as mandatory and issued airworthiness 
directives 010-09-95 (for Model SD3-60 series airplanes)

[[Page 39365]]

and 009-09-95 (for Model SD3-SHERPA series airplanes), in order to 
assure the continued airworthiness of these airplanes in the United 
Kingdom.

FAA's Conclusions -

    These airplane models are manufactured in the United Kingdom 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 CAA has kept the FAA 
informed of the situation described above. The FAA has examined the 
findings of the CAA, 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, the 
proposed AD would require a one-time visual and fluorescent dye 
penetrant inspection to detect cracks and/or corrosion of the gland nut 
on the shock absorber of the MLG, and repair or replacement of the 
gland nut with a new nut, if necessary. Following the accomplishment of 
the inspection, the proposed AD also would require applying grease to 
the threads of the cylinder and applying sealant to the inner radius of 
the gland nut. The actions would be required to be accomplished in 
accordance with the service bulletins described previously.

Cost Impact -

    The FAA estimates that 88 airplanes (72 Model SD3-60 series 
airplanes and 16 Model SD3-SHERPA series airplanes) of U.S. registry 
would be affected by this proposed AD, that it would take approximately 
5 work hours per airplane to accomplish the proposed actions, and that 
the average labor rate is $60 per work hour. Based on these figures, 
the cost impact of the proposed AD on U.S. operators is estimated to be 
$26,400, or $300 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:

Short Brothers, PLC: Docket 96-NM-09-AD.

    -Applicability: Model SD3-60 and Model SD3-SHERPA series 
airplanes, as listed in Shorts Service Bulletin SD360-32-34 (for 
Model SD3-60 series airplanes), and Shorts Service Bulletin SD3 
SHERPA-32-2 (for Model SD3-SHERPA series airplanes), both dated 
September 22, 1995; 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 stress corrosion or cracking of the gland nut on the 
shock absorber of the main landing gear (MLG) and consequent reduced 
structural integrity of the nut, which could result in separation of 
the shock absorber cylinder from the MLG shock absorber body and, 
consequently, lead to the collapse of the MLG during landing; 
accomplish the following: -
    (a) Within 90 days after the effective date of this AD, perform 
a one-time visual and fluorescent dye penetrant inspection to detect 
cracks and/or corrosion of the gland nut on the shock absorber of 
the MLG, in accordance with Shorts Service Bulletin SD360-32-34 (for 
Model SD3-60 series airplanes), and Shorts Service Bulletin SD3 
SHERPA-32-2 (for Model SD3-SHERPA series airplanes), both dated 
September 22, 1995, as applicable.

    -Note 2: Shorts Service Bulletins SD360-32-34 and SD3 SHERPA-32-
2 reference Messier-Dowty Service Bulletin 32-78SD, dated July 19, 
1995, as an additional source of service information.

    -(1) If no crack and/or corrosion is detected, no further action 
is required by paragraph (a) of this AD. -
    (2) If no crack is detected, but corrosion is detected that is 
within the limits specified in the service bulletin, prior to 
further flight, repair the gland nut in accordance with the 
applicable service bulletin. -
    (3) If any crack is detected, or if any corrosion is detected 
that is outside the limits specified in the service bulletin, prior 
to further flight, replace the gland nut with a new gland nut, in 
accordance with the applicable service bulletin. -
    (b) Following accomplishment of paragraph (a) of this AD, prior 
to further flight, apply grease to the threads of the cylinder, and 
apply sealant to the inner radius of the gland nut, in accordance 
with Shorts Service Bulletin SD360-32-34 (for Model SD3-60 series 
airplanes), and Shorts Service Bulletin SD3 SHERPA-32-2 (for Model 
SD3-SHERPA series airplanes), both dated September 22, 1995, as 
applicable. -
    (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, 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 3: Information concerning the existence of approved 
alternative methods of compliance with this AD, if any, may be 
obtained from the Standardization Branch, ANM-113. -

[[Page 39366]]

    (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.
    Issued in Renton, Washington, on July 23, 1996.
John J. Hickey,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 96-19150 Filed 7-26-96; 8:45 am]
BILLING CODE 4910-13-P