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

DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 98-NM-137-AD; Amendment 39-11367; AD 99-21-22]

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 a visual inspection to

detect corrosion of the shear decks and ribs of the left and right stub

wings; follow-on corrective actions, if necessary; and drilling of new

drain holes in the lower shear decks. 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 corrosion of the stub wing shear decks and ribs,

which could result in cracking or failure of the stub wing structure.

DATES: Effective November 17, 1999.

The incorporation by reference of certain publications listed in

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

of November 17, 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 23, 1999 (64 FR 33439). That action

proposed to require a one-time borescope inspection to detect corrosion

of the shear decks and ribs of the left and right stub wings, follow-on

corrective actions, if necessary; and drilling of new drain holes in

the lower shear decks.

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 Revise Inspection Method

One commenter suggests that the proposed AD be revised to include

instructions to remove the main landing gear (MLG) forward pintle pin

(which requires removal of the wheel lever assemblies) and to steam

clean the areas identified by the referenced service bulletin. The

commenter also suggests that all reference to use of a borescope be

deleted to prevent misinterpretation. The commenter states that the

proposed AD dictates a different inspection method than the referenced

manufacturer's service bulletin, since it does not reference removing

the MLG or steam cleaning the area, and requires a borescope

inspection. Such a method may actually degrade safety, since without

removal of the MLG forward pintle pins, thorough cleaning and

subsequent inspection of the area cannot be accomplished. The commenter

states that most technicians

[[Page 55410]]

would interpret the requirement to use a borescope to mean that removal

of the MLG is not required, since the purpose of a borescope is to

enable inspection without disassembly.

The FAA has determined that clarification of the AD is necessary.

The intent of the AD is to require the same inspection methods

specified in the referenced service bulletins. The actions required by

paragraph (a) of the AD are specifically required to be accomplished in

accordance with Part A of the Accomplishment Instructions of the

applicable service bulletin. Part A includes instructions for removal

of the port and starboard MLG, and steam cleaning of the affected area,

prior to inspection. Part A, paragraph 7., also specifies to ``visually

inspect inner surfaces and interfaces between ribs for corrosion using

a borescope.'' The FAA does not specify in an AD each action described

in the referenced service information, since such restatement would be

unnecessarily duplicative and could result in misunderstanding of the

requirements. However, to avoid any confusion as to the actions

required by this AD, the FAA has revised paragraph (a) of the AD to

require that all actions in Part A of the service bulletin be

accomplished. The FAA has also restated the borescope inspection

requirement to specify a ``visual inspection using a borescope.''

Request To Allow Use of Alternate Service Information

One commenter requests that the proposed AD be revised to allow

accomplishment of the required inspections on Short Brothers Model SD3-

60 SHERPA airplanes having serial numbers SH3420 through SH3428 in

accordance with Shorts Service Bulletin SD360-53-43, Revision 1, dated

November 27, 1998. This service bulletin was specified in the proposed

AD as the appropriate source of service information for Model SD3-60

airplanes, and SD360-Sherpa-53-4, dated November 27, 1998, was

specified as appropriate for Model SD3-60 SHERPA airplanes. The

commenter provides documentation showing that the airplane manufacturer

has previously accomplished service bulletin SD360-53-43 on certain

Model SD3-60 SHERPA airplanes, and requests that the FAA consider such

action to be adequate for compliance with the inspection required by

this AD.

The FAA concurs. The actions described in Shorts Service Bulletins

SD360-53-43, Revision 1, and SD360-Sherpa-53-4 are substantially

equivalent. The FAA has determined that for Model SD3-60 SHERPA series

airplanes, inspections accomplished in accordance with SD360-53-43,

dated November 4, 1997, or Revision 1, dated November 27, 1998, are

acceptable for compliance with the initial inspection required by

paragraph (a) of this AD. A ``NOTE'' has been added to the final rule

to provide such credit.

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 112 airplanes of U.S. registry will be

affected by this AD, that it will take approximately 100 work hours per

airplane to accomplish the required inspection, 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 $672,000, or

$6,000 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:

99-21-22 Short Brothers PLC: Amendment 39-11367. Docket 98-NM-137-

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 (e) 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 corrosion of the stub wing shear decks and ribs,

which could result in cracking or failure of the stub wing

structure, accomplish the following:

Inspection and Corrective Actions

(a) Within 6 months after the effective date of this AD,

accomplish all actions, including a visual inspection using a

borescope, specified in Part A of the Accomplishment Instructions of

the applicable Shorts Service Bulletin specified below, all dated

November 27, 1998 (hereinafter referred to as the applicable service

bulletin), in the areas of the stub wing shear decks and ribs to

detect corrosion, and drill new drain holes in the lower shear

decks, in accordance with the applicable service bulletin:

SD330-53-68 (for Model SD3-30 series airplanes);

SD360-53-43, Revision 1 (for Model SD3-60 series

airplanes);

SD3 Sherpa-53-4 (for Model SD3 SHERPA series

airplanes); and

[[Page 55411]]

SD360-Sherpa-53-4 (for Model SD3-60 SHERPA series

airplanes).

Note 2: In the case where no corrosion is detected during the

inspection described in Part A of the Accomplishment Instructions of

the applicable service bulletin, the service bulletin specifies

accomplishment of follow-on repetitive inspections of this area as

specified in Short Brothers Aircraft Maintenance Programme, Chapter

5-26-57.

Note 3: For Model SD3-60 SHERPA series airplanes, accomplishment

of the actions required by paragraph (a) of this AD in accordance

with Shorts Service Bulletin SD360-53-43, dated November 4, 1997, or

Revision 1, dated November 27, 1998, is acceptable for compliance

with the requirements of that paragraph.

(b) Except as provided by paragraph (c) of this AD: If any

corrosion is detected during the inspection required by paragraph

(a) of this AD, prior to further flight, accomplish corrective

actions (i.e., additional inspections, removal of corrosion,

replacement of components), as applicable, in accordance with Part B

of the Accomplishment Instructions of the applicable service

bulletin. Thereafter, repeat the inspection required by paragraph

(a) of this AD at intervals not to exceed 12 months.

(c) If any corrosion condition is found for which the applicable

service bulletin specifies that Short Brothers is to be contacted

for an appropriate repair action: Prior to further flight, repair in

accordance with a method approved by either the Manager,

International Branch, ANM-116, FAA, Transport Airplane Directorate,

or the Civil Aviation Authority (CAA) of the United Kingdom (or its

delegated agent).

Reporting Requirement

(d) Within 10 days after accomplishment of the initial

inspection required by paragraph (a) of this AD, or within 30 days

after the effective date of this AD, whichever occurs later, submit

a report of the inspection findings (positive or negative) to: Team

Leader, Service Engineering-Aerospace Customer Support Short

Brothers plc, Belfast, N. Ireland. Information collection

requirements contained in this regulation have been approved by the

Office of Management and Budget (OMB) under the provisions of the

Paperwork Reduction Act of 1980 (44 U.S.C. 3501 et seq.) and have

been assigned OMB Control Number 2120-0056.

Alternative Methods of Compliance

(e) 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.

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 4: 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

(f) 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

(g) The actions shall be done in accordance with Shorts Service

Bulletin SD330-53-68, dated November 27, 1998, Shorts Service

Bulletin SD360-53-43, Revision 1, dated November 27, 1998, Shorts

Service Bulletin SD3 Sherpa-53-4, dated November 27, 1998, or Shorts

Service Bulletin SD360-Sherpa-53-4, dated November 27, 1998; as

applicable. 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 Short Brothers,

Airworthiness & Engineering Quality, P.O. Box 241, Airport Road,

Belfast BT3 9DZ, Northern Ireland. 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 5: The subject of this AD is addressed in British

airworthiness directives 006-11-97, 006-11-98, 007-11-98, and 008-

11-98.

(h) This amendment becomes effective on November 17, 1999.

Issued in Renton, Washington, on October 4, 1999.

D. L. Riggin,

Acting Manager, Transport Airplane Directorate, Aircraft Certification

Service.

[FR Doc. 99-26277 Filed 10-12-99; 8:45 am]

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