Airworthiness Directives; Short Brothers Model SD3-30, SD3-60, SD3-SHERPA, and SD3-60 SHERPA Series Airplanes

Federal RegisterOct 1, 1999

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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 99-NM-29-AD; Amendment 39-11345; AD 99-21-02]

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: Final rule.

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SUMMARY: This amendment adopts a new airworthiness directive (AD),

applicable to all Short Brothers Model SD3-30, SD3-60, SD3-SHERPA, and

SD3-60 SHERPA series airplanes, that requires detailed visual and

borescopic inspections to detect corrosion of the engine mounting tube

assembly, and replacement of corroded parts with new or serviceable

parts. 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 failure of the

engine mounting tube assembly, which could result in loss of the engine

in flight.

DATES: Effective November 5, 1999.

The incorporation by reference of certain publications listed in

the regulations is approved by the Director of the Federal Register as

of November 5, 1999.

ADDRESSES: The service information referenced in this AD 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 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 all Short Brothers Model SD3-30,

SD3-60, SD3-SHERPA, and SD3-60 SHERPA series airplanes was published in

the Federal Register on June 28, 1999 (64 FR 34582). That action

proposed to require detailed visual and borescopic inspections to

detect corrosion of the engine mounting tube assembly, and replacement

of corroded parts with new or serviceable parts.

Comments Received

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 Extend Compliance Time

The manufacturer requests that the FAA extend the proposed

compliance time from 6 months to 9 months. The manufacturer supports

its request based on the results of an airframe structural analysis,

ongoing inspections, and the Civil Aviation Authority of the United

Kingdom's acceptance of the 3-month extension. The FAA has reviewed the

data presented by the manufacturer and concurs with the request. The

final rule has been revised accordingly.

Explanation of Additional Change to Proposal

The FAA has added a note to the final rule to clarify the

definition of a 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 137 Model SD3-30, SD3-60, SD3-SHERPA, and

SD3-60 SHERPA series airplanes of U.S. registry will be affected by

this AD, that it will take approximately 25 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 cost impact of the 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 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:

99-21-02 Short Brothers PLC: Amendment 39-11345. 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

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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 9 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 Bulletins 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); SD3-60

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 the pin with a new or serviceable pin.

Note 2: For the purposes of this AD, a detailed visual

inspection is defined as: ``As an 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 light 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.''

(b) Within 9 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