[Federal Register Volume 59, Number 35 (Tuesday, February 22, 1994)]
[Unknown Section]
[Page 0]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 94-3752]


[[Page Unknown]]

[Federal Register: February 22, 1994]


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DEPARTMENT OF TRANSPORTATION
14 CFR Part 39

[Docket No. 93-NM-149-AD; Amendment 39-8829; AD 94-04-09]

 

Airworthiness Directives; de Havilland, Inc., Model DHC-8-100 and 
DHC-8-300 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 certain de Havilland Model DHC-8-100 and DHC-8-300 series 
airplanes, that requires inspections to detect breakage in the engine 
rear mount strut assemblies, and replacement of broken struts. This 
amendment also requires eventual replacement of all currently installed 
struts with new and/or reworked struts, as terminating action for the 
inspections. This amendment is prompted by several reports of failure 
of the engine rear mount struts, due to fracture at one of the rosette 
welds on the shank of the strut where full weld depth was not achieved 
during manufacture. The actions specified by this AD are intended to 
prevent fracture of the engine rear mount struts, which could reduce 
the structural integrity of the nacelle and engine support structure.

DATES: Effective March 24, 1994.
    The incorporation by reference of certain publications listed in 
the regulations is approved by the Director of the Federal Register as 
of March 24, 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: Jon Hjelm, Aerospace Engineer, 
Airframe Branch, ANE-172, FAA, Engine and Propeller Directorate, 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-8-100 and DHC-8-300 series 
airplanes was published in the Federal Register on October 25, 1993 (58 
FR 55031). That action proposed to require repetitive detailed visual 
inspections to detect breakage in the engine strut assemblies, and 
replacement of broken struts with new and/or reworked struts. That 
action also proposed to require eventual replacement of the currently 
installed struts with new and/or reworked struts; when accomplished, 
this replacement would terminate the need for the repetitive 
inspections.
    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 125 airplanes of U.S. registry will be 
affected by this AD, that it will take approximately 16 work hours per 
airplane to accomplish the required actions, and that the average labor 
rate is $55 per work hour. Required parts will be provided by the 
manufacturer at no cost to the operators. Based on these figures, the 
total cost impact of the AD on U.S. operators is estimated to be 
$110,000, or $880 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.


Sec. 39.13  [Amended] -

    2. Section 39.13 is amended by adding the following new 
airworthiness directive:

94-04-09 De Havilland, Inc.: Amendment 39-8829. Docket 93-NM-149-AD.

     -Applicability: Model DHC-8-102 and -103 series airplanes, 
serial numbers 003 through 310 inclusive; and Model DHC-8-301, -311, 
and -314 series airplanes, serial numbers 100 through 311 inclusive, 
certificated in any category. -
    Compliance: Required as indicated, unless accomplished 
previously.
    To prevent fracture of the engine rear mount struts, and 
subsequent reduced structural integrity of the nacelle and engine 
support structure, accomplish the following: -
    (a) Within 50 hours time-in-service after the effective date of 
this AD, perform a detailed visual inspection to detect breakage in 
the engine strut assemblies, part number 8711016-001, -003, -005, or 
-007, in accordance with De Havilland, Inc., Service Bulletin S.B. 
8-71-17, dated April 3, 1992. -
    (1) If any broken strut is detected, prior to further flight, 
replace the broken strut with a new strut, part number 87110016-009, 
or a reworked strut, part number 8DK1763-001; Post-Modification 8/
1763; in accordance with the service bulletin.

     -Note 1: The Post-Modification 8/1763 struts are either new 
struts, part number 87110016-009, or reworked struts, part number 
8DK1763-001.

     -(2) If no broken strut is detected, repeat the inspection 
thereafter at intervals not to exceed 50 flight hours.
    (b) Within 24 months after the effective date of this AD, 
replace all of the currently installed engine rear mount struts with 
new struts, part number 87110016-009, and/or reworked struts, part 
number 8DK1763-001; Post-Modification 8/1763; in accordance with de 
Havilland, Inc., Service Bulletin S.B. 8-71-17, dated April 3, 1992. 
This replacement constitutes terminating action for the repetitive 
inspection requirements of this AD.
    (c) As of the effective date of this AD, no person shall install 
an engine rear mount strut, part number 8711016-001, -003, -005, or 
-007, on any airplane.
    (d) 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 Aircraft Certification 
Office (ACO), 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 2: Information concerning the existence of approved 
alternative methods of compliance with this AD, if any, may be 
obtained from the New York ACO.

    (e) 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.
    (f) The inspections and replacements shall be done in accordance 
with de Havilland, Inc., Service Bulletin S.B. 8-71-17, dated April 
3, 1992. 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.
    (g) This amendment becomes effective on March 24, 1994.

    Issued in Renton, Washington, on Feburary 14, 1994.
Darrell M. Pederson,
 Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 94-3752 Filed 2-18-94; 8:45 am]
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