[Federal Register Volume 64, Number 123 (Monday, June 28, 1999)]
[Proposed Rules]
[Pages 34582-34584]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 99-16332]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 99-NM-29-AD]
RIN 2120-AA64


Airworthiness Directives; Short Brothers Model SD3-30, SD3-60, 
SD3-SHERPA, and SD3-60 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 all Short Brothers Model SD3-30, 
SD3-60, SD3-SHERPA, and SD3-60 SHERPA series airplanes. This proposal 
would require detailed visual and borescopic inspections to detect 
corrosion of the

[[Page 34583]]

engine mounting tube assembly, and replacement of corroded parts with 
new or serviceable parts. This proposal is prompted by issuance of 
mandatory continuing airworthiness information by a foreign civil 
airworthiness authority. The actions specified by the proposed AD are 
intended to prevent failure of the engine mounting tube assembly, which 
could result in loss of the engine in flight.

DATES: Comments must be received by July 28, 1999.

ADDRESSES: Submit comments in triplicate to the Federal Aviation 
Administration (FAA), Transport Airplane Directorate, ANM-114, 
Attention: Rules Docket No. 99-NM-29-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, Airworthiness & Engineering Quality, P.O. 
Box 241, Airport Road, Belfast BT3 9DZ, Northern Ireland. This 
information may be examined at the FAA, Transport Airplane Directorate, 
1601 Lind Avenue, SW., Renton, Washington.

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:

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 99-NM-29-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-114, Attention: Rules 
Docket No. 99-NM-29-AD, 1601 Lind Avenue, SW., Renton, Washington 
98055-4056.

Discussion

    The Civil Aviation Authority (CAA), which is the airworthiness 
authority for the United Kingdom, notified the FAA that an unsafe 
condition may exist on all Short Brothers Model SD3-30, SD3-60, SD3-
SHERPA, and SD3-60 SHERPA series airplanes. The CAA advises that 
corrosion has been found on and in the engine mounting tube assembly of 
two Model SD3-60 series airplanes. Specifically, corrosion was found on 
the internal surface of the engine mounting tubes, and on the tube end 
fittings, taper pins, and foot fittings. This condition may exist on 
all four Short Brothers models due to the similarity in design of the 
engine mounting asssembly for each model. Such corrosion, if not 
corrected, could result in failure of the engine mounting tube assembly 
and consequent loss of the engine in flight.

Explanation of Relevant Service Information

    The manufacturer has issued Shorts Service Bulletins SD330-71-23, 
dated November 20, 1998, and Revision 1, dated April 26, 1999 (for 
Model SD3-30 series airplanes); SD3 SHERPA 71-1, Revision 1, dated 
February 3, 1999, and Revision 2, dated April 26, 1999 (for Model SD3-
SHERPA series airplanes); SD360 SHERPA 71-1, Revision 1, dated February 
3, 1999, and Revision 2, dated April 26, 1999 (for Model SD3-60 SHERPA 
series airplanes); and SD360-71-18, Revision 1, dated February 3, 1999, 
and Revision 2, dated April 26, 1999 (for Model SD3-60 series 
airplanes). These service bulletins describe procedures for detailed 
visual and borescopic inspections to detect corrosion of the engine 
mounting tube assembly, and replacement of corroded parts with new or 
serviceable parts. Accomplishment of the actions specified in the 
service bulletins is intended to adequately address the identified 
unsafe condition. The CAA classified these service bulletins as 
mandatory and issued British airworthiness directives 014-11-98, 018-
11-98, 011-11-98, and 012-11-98 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 Sec. 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 registered 
in the United States, the proposed AD would require accomplishment of 
the actions specified in the service bulletins described previously, 
except as discussed below.

Difference Between Proposed Rule and Foreign AD's

    The proposed AD would differ from the parallel CAA airworthiness 
directives in that it does not require the operator to submit the 
inspection results to the manufacturer. Because the manufacturer has 
provided a terminating action, the FAA has determined that reporting 
inspection results is not necessary. However, the operator at its 
discretion may choose otherwise.

Differences Between Proposed Rule and Service Bulletins

    The compliance times proposed by this AD would differ from those 
specified by the most recent versions of the referenced service 
bulletins. Those revised service bulletins recommend a 9-month 
compliance time; the proposed AD would require a 6-month compliance 
time, which is the same as that required by the parallel CAA 
airworthiness directives. The FAA is not aware of any information that 
would justify a 9-month compliance time.

[[Page 34584]]

Cost Impact

    The FAA estimates that 137 airplanes of U.S. registry would be 
affected by this proposed AD, that it would take approximately 25 work 
hours per airplane to accomplish the proposed inspection, 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 
$205,500, or $1,500 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 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 99-NM-29-AD.

    Applicability: All Model SD3-30, SD3-60, SD3-SHERPA, and SD3-60 
SHERPA series airplanes; 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 failure of the engine mounting tube assembly, which 
could result in loss of the engine in flight, accomplish the 
following:

Inspections

    (a) Within 6 months after the effective date of this AD, perform 
a detailed visual inspection of the taper pins of the engine 
mounting tube assembly for corrosion, in accordance with Shorts 
Service Bulletin SD330-71-23, dated November 20, 1998, or Revision 
1, dated April 26, 1999 (for Model SD3-30 series airplanes); SD 3 
SHERPA--71-1, Revision 1, dated February 3, 1999, or Revision 2, 
dated April 26, 1999 (for Model SD3-SHERPA series airplanes); SD360 
SHERPA 71-1, Revision 1, dated February 3, 1999, or Revision 2, 
dated April 26, 1999 (for Model SD3-60 SHERPA series airplanes); or 
SD360-71-18, Revision 1, dated February 3, 1999, or Revision 2, 
dated April 26, 1999 (for Model SD3-60 series airplanes); as 
applicable. If corrosion is found on any taper pin, prior to further 
flight, replace all three pins with new or serviceable pins, in 
accordance with the applicable service bulletin.
    (b) Within 6 months after the effective date of this AD, perform 
a borescopic inspection of the internal surface of the engine 
mounting tubes and fittings for corrosion, in accordance with Shorts 
Service Bulletin SD330-71-23, dated November 20, 1998, or Revision 
1, dated April 26, 1999 (for Model SD3-30 series airplanes); SD3 
SHERPA--71-1, Revision 1, dated February 3, 1999, or Revision 2, 
dated April 26, 1999 (for Model SD3-SHERPA series airplanes); SD360 
SHERPA 71-1, Revision 1, dated February 3, 1999, or Revision 2, 
dated April 26, 1999 (for Model SD3-60 SHERPA series airplanes); or 
SD360-71-18, Revision 1, dated February 3, 1999, or Revision 2, 
dated April 26, 1999 (for Model SD3-60 series airplanes); as 
applicable.
    (1) If no corrosion is found on the internal surface of the 
engine mounting tubes and fittings, no further action is required by 
this paragraph.
    (2) If corrosion is found that is within the limits as defined 
in the applicable service bulletin, repeat the borescopic inspection 
thereafter at intervals not to exceed 6 months. Replacement of all 
corroded parts with new or serviceable parts in accordance with the 
applicable service bulletin constitutes terminating action for the 
repetitive borescopic inspections required by this AD.
    (3) If corrosion is found that is outside the limits as defined 
in the applicable service bulletin, prior to further flight, replace 
the corroded parts with new or serviceable parts, in accordance with 
the applicable service bulletin.

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 2: 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 
Sec. Sec. 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.

    Note 3: The subject of this AD is addressed in British 
airworthiness directives 014-11-98, 018-11-98, 011-11-98, and 012-
11-98.

    Issued in Renton, Washington, on June 22, 1999.
D.L. Riggin,
 Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 99-16332 Filed 6-25-99; 8:45 am]
BILLING CODE 4910-13-U