Airworthiness Directives; de Havilland, Inc., Model DHC-7 Series Airplanes

DEPARTMENT OF TRANSPORTATION

14 CFR Part 39

[Docket No. 92-NM-157-AD; Amendment 39-8893; AD 94-09-05]

Airworthiness Directives; de Havilland, Inc., Model DHC-7 Series

Airplanes

AGENCY: Federal Aviation Administration, DOT.

ACTION: Final rule.

-----------------------------------------------------------------------

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

applicable to certain de Havilland Model DHC-7 series airplanes, that

requires a one-time inspection to assess the adequacy of the clearance

between various adapter plates and seal retaining angles on the

fuselage side access panel, and modification of both the forward and

rear seal retention angles. This amendment is prompted by reports of

incidents involving corrosion and fatigue cracking in commuter-class

airplanes that are approaching or have exceeded their economic design

goal. The actions specified by this AD are intended to prevent

degradation of the structural capabilities of the affected airplanes.

DATES: Effective June 6, 1994.

The incorporation by reference of certain publications listed in

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

of June 6, 1994.

ADDRESSES: The service information referenced in this AD may be

obtained from de Havilland, Inc., Garratt Boulevard, Downsview, Ontario

M3K 1Y5, Canada. 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 FAA,

Engine and Propeller Directorate, New York Aircraft Certification

Office, 181 South Franklin Avenue, room 202, Valley Stream, New York;

or at the Office of the Federal Register, 800 North Capitol Street,

NW., suite 700, Washington, DC.

FOR FURTHER INFORMATION CONTACT: Sol Maroof, Aerospace Engineer,

Airframe Branch, ANE-172, FAA, New York Aircraft Certification Office,

181 South Franklin Avenue, room 202, Valley Stream, New York 11581;

telephone (516) 791-6220; fax (516) 791-9024.

SUPPLEMENTARY INFORMATION: A proposal to amend part 39 of the Federal

Aviation Regulations to include an airworthiness directive (AD) that is

applicable to certain de Havilland Model DHC-7 series airplanes was

published as a supplemental notice of proposed rulemaking (NPRM) in the

Federal Register on January 4, 1994 (59 FR 266). That action proposed

to require a one-time inspection to assess the adequacy of the

clearance between various adapter plates and seal retaining angles on

the fuselage side access panel, and modification of both the forward

and rear seal retention angles.

Interested persons have been afforded an opportunity to participate

in the making of this amendment. Due consideration has been given to

the single comment received.

The commenter supports the proposed rule.

After careful review of the available data, including the comment

noted above, the FAA has determined that air safety and the public

interest require the adoption of the rule as proposed.

The FAA estimates that 44 airplanes of U.S. registry will be

affected by this AD, that it will take approximately 8 work hours per

airplane to accomplish the modifications and inspections, and that the

average labor rate is $55 per work hour. Required parts will be nominal

in cost. Based on these figures, the total cost impact of the AD on

U.S. operators is estimated to be $19,360, or $440 per airplane.

The total 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.

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 14 CFR part

39 of the Federal Aviation Regulations as follows:

PART 39--AIRWORTHINESS DIRECTIVES

1. The authority citation for part 39 continues to read as follows:

Authority: 49 U.S.C. App. 1354(a), 1421 and 1423; 49 U.S.C.

106(g); and 14 CFR 11.89.

39.13 [Amended]

2. Section 39.13 is amended by adding the following new

airworthiness directive:

94-09-05 De Havilland, Inc.: Amendment 39-8893. Docket 92-NM-157-AD.

Applicability: Model DHC-7 series airplanes having serial

numbers 1 through 99 inclusive, certificated in any category.

Compliance: Required as indicated, unless accomplished

previously.

To prevent structural failure, accomplish the following:

(a) For airplanes having serial numbers 1 through 77 inclusive,

79 through 83 inclusive, 85, and 86: Within 12 months after the

effective date of this AD, inspect the clearance between the wing

forward pick-up adapter plates and the seal retaining angle on the

fuselage side access panel in accordance with de Havilland Service

Bulletin 7-57-11, dated December 17, 1982.

(1) If the adapter plates are undamaged or if scoring on the

adapter plates does not exceed 0.050 inch in depth, prior to further

flight, accomplish Modification 7/2319 in accordance with the

service bulletin.

(2) If scoring on the adapter plates is equal to or exceeds

0.050 inch in depth, prior to further flight, repair in accordance

with a method approved by the Manager, New York Aircraft

Certification Office (ACO), ANE-170, FAA, Engine and Propeller

Directorate.

(b) For airplanes having serial numbers 1 through 99 inclusive:

Within 12 months after the effective date of this AD, inspect the

clearance between the rear mounting adapter plates and the seal

retaining angle on the fuselage side access panel in accordance with

de Havilland Service Bulletin 7-57-19, dated February 24, 1984.

(1) If the adapter plates are undamaged or if scoring on the

adapter plates does not exceed 0.050 inch in depth, prior to further

flight, accomplish Modification 7/2355 in accordance with the

service bulletin.

(2) If scoring on the adapter plates is equal to or exceeds

0.050 inch in depth, prior to further flight, repair in accordance

with a method approved by the Manager, New York ACO, ANE-170, FAA,

Engine and Propeller Directorate.

(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, New York ACO, ANE-170, FAA, Engine

and Propeller Directorate. Operators shall submit their requests

through an appropriate FAA Principal Maintenance Inspector, who may

add comments and then send it to the Manager, New York ACO.

Note: Information concerning the existence of approved

alternative methods of compliance with this AD, if any, may be

obtained from the New York ACO.

(d) Special flight permits may be issued in accordance with

Federal Aviation Regulations (FAR) 21.197 and 21.199 to operate the

airplane to a location where the requirements of this AD can be

accomplished.

(e) The inspections and modifications shall be done in

accordance with de Havilland Service Bulletin 7-57-11, dated

December 17, 1982, and de Havilland Service Bulletin 7-57-19, dated

February 24, 1984. 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 de Havilland,

Inc., Garratt Boulevard, Downsview, Ontario M3K 1Y5, Canada. Copies

may be inspected at the FAA, Transport Airplane Directorate, 1601

Lind Avenue, SW., Renton, Washington; or at the FAA, Engine and

Propeller Directorate, New York Aircraft Certification Office, 181

South Franklin Avenue, Room 202, Valley Stream, New York; or at the

Office of the Federal Register, 800 North Capitol Street, NW., suite

700, Washington, DC.

(f) This amendment becomes effective on June 6, 1994.

Issued in Renton, Washington, on April 18, 1994.

Darrell M. Pederson, Acting Manager,

Transport Airplane Directorate, Aircraft Certification Service.

[FR Doc. 94-9730 Filed 5-4-94; 8:45 am]

BILLING CODE 4910-13-U