[Federal Register Volume 61, Number 190 (Monday, September 30, 1996)]
[Proposed Rules]
[Pages 51062-51064]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 96-24890]


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DEPARTMENT OF TRANSPORTATION
14 CFR Part 39

[Docket No. 95-NM-265-AD]
RIN 2120-AA64


Airworthiness Directives; de Havilland Model DHC-7 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 de Havilland Model DHC-7 
series airplanes. This proposal would require performing a review of 
the airplane maintenance records to determine if any insulation 
blankets have been repaired or changed during service, and various 
follow- on actions, if necessary. This proposal is prompted by reports 
of corrosion forming on areas of the airplane structure where black 
film thermal insulation blankets are used. The actions specified by the 
proposed AD are intended to prevent such corrosion, which could result 
in degradation of the structural capability of the airplane fuselage 
and consequent sudden loss of cabin pressure.

DATES: Comments must be received by November 8, 1996.

ADDRESSES: Submit comments in triplicate to the Federal Aviation 
Administration (FAA), Transport Airplane Directorate, ANM-103, 
Attention: Rules Docket No. 95-NM-265-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 Bombardier, Inc., Bombardier Regional Aircraft Division, 
Garratt Boulevard, Downsview, Ontario M3K 1Y5, Canada. This information 
may be examined at the FAA, Transport Airplane Directorate, 1601 Lind 
Avenue, SW., Renton, Washington.

FOR FURTHER INFORMATION CONTACT: Sol Maroof, Aerospace Engineer, 
Airframe and Propulsion Branch, ANE-171, FAA, New York Aircraft 
Certification Office, Engine and Propeller Directorate, 10 Fifth 
Street, Third Floor, Valley Stream, New York 11581; telephone (516) 
256-7522; fax (516) 568-2716.

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 95-NM-265-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-103, Attention: Rules 
Docket No. 95-NM-265-AD, 1601 Lind Avenue, SW., Renton, Washington 
98055-4056.

Discussion

    Transport Canada Aviation, which is the airworthiness authority for 
Canada, recently notified the FAA that an unsafe condition may exist on 
all de Havilland Model DHC-7 series airplanes. Transport Canada advises 
that it has received reports of corrosion forming on areas of the 
airplane structure where black Orcon film covers the thermal insulation 
blankets. Investigation revealed that the black Orcon film, used to 
insulate the airplane, contains carbon. The cause of this corrosion has 
been attributed to the formation of condensation on aluminum airplane 
structure where the structure comes in contact with the carbon in the 
black Orcon film. Such corrosion, if not detected and corrected in a 
timely manner, could result in degradation of the strength of the 
airplane fuselage structure and, consequently, could lead to sudden 
loss of cabin pressure.

[[Page 51063]]

Explanation of Relevant Service Information

    Bombardier has issued Service Bulletin S.B. 7-21-30, dated July 6, 
1994, which describes procedures for performing the following:
    1. A review of the airplane maintenance records to determine if any 
insulation blankets have been repaired or changed during service;
    2. A visual inspection to detect black film insulation of the air 
conditioning system, if any insulation has been repaired or changed 
during service, or if a certain kit is installed;
    3. A review of the airplane modification records to determine if 
certain kits have been installed, if no black film insulation is 
detected; and
    4. Various follow-on actions, if any black film insulation is 
detected. (The follow-on actions include removal of any black film 
insulation, an inspection to detect corrosion, repair of any corroded 
structure, and installation of new silver blankets.)
    Transport Canada Aviation classified this service bulletin as 
mandatory and issued Canadian airworthiness directive CF-94-24, dated 
December 22, 1994, in order to assure the continued airworthiness of 
these airplanes in Canada.

FAA's Conclusions

    This airplane model is manufactured in Canada and is type 
certificated for operation in the United States under the provisions of 
section 21.29 of the Federal Aviation Regulations (14 CFR 21.29) and 
the applicable bilateral airworthiness agreement. Pursuant to this 
bilateral airworthiness agreement, Transport Canada Aviation has kept 
the FAA informed of the situation described above. The FAA has examined 
the findings of Transport Canada Aviation, 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, the 
proposed AD would require performing a review of the airplane 
maintenance records to determine if any insulation blankets have been 
repaired or changed during service, and various follow-on actions, if 
necessary. The actions would be required to be accomplished in 
accordance with the service bulletin described previously. The repair 
of any corroded structure would be required to be accomplished in 
accordance with a method approved by the FAA.

Other Relevant Rulemaking

    The FAA previously issued a proposed AD that is similar to this 
action. That proposed AD [reference Docket 84-NM-89-AD (61 FR 13785, 
March 28, 1996)] is applicable to de Havilland Model DHC-8 series 
airplanes and would require actions similar to those proposed in this 
notice.

Cost Impact

    The FAA estimates that 50 de Havilland Model DHC-7 series airplanes 
of U.S. registry would be affected by this proposed AD, that it would 
take approximately 1 work hour per airplane to accomplish the proposed 
actions, 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 $3,000, or $60 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 (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:

De Havilland, Inc.: Docket 95-NM-265-AD.
    Applicability: All Model DHC-7 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 
otherwise 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 use the authority 
provided in paragraph (e) of this AD to request approval from the 
FAA. This approval may address either no action, if the current 
configuration eliminates the unsafe condition; or different actions 
necessary to address the unsafe condition described in this AD. Such 
a request should include an assessment of the effect of the changed 
configuration on the unsafe condition addressed by this AD. In no 
case does the presence of any modification, alteration, or repair 
remove any airplane from the applicability of this AD.

    Compliance: Required as indicated, unless accomplished 
previously.
    To prevent degradation of the structural capability of the 
fuselage and sudden loss of cabin pressure, accomplish the 
following:
    (a) Within six months after the effective date of this AD, 
perform a review of the airplane maintenance records to determine if 
any insulation blankets have been repaired or changed during 
service, in accordance with de Havilland Service Bulletin S.B. 7-21-
30, dated July 6, 1994.
    (b) If no insulation blanket has been repaired or changed, no 
further action is required by this AD.
    (c) If any insulation blanket has been repaired or changed, 
prior to further flight, perform a visual inspection to detect black 
film insulation of the air conditioning system, in accordance with 
de Havilland Service Bulletin S.B. 7-21-30, dated July 6, 1994.
    (1) If no black film insulation is detected, prior to further 
flight, perform a review of the airplane modification records to 
determine if any kit listed in ``Table 1--Modification List'' has 
been installed, in accordance with the service bulletin.

[[Page 51064]]

    (i) If no kit listed in Table 1--Modification List is found to 
be installed, no further action is required by this AD.
    (ii) If any kit listed in Table 1 is found to be installed, 
prior to further flight, perform the various follow-on actions in 
accordance with the service bulletin. (The follow-on actions include 
an inspection to detect black film insulation, removal of any black 
film insulation, an inspection to detect corrosion, repair of 
corroded structure, and installation of new silver blankets.) 
However, in lieu of repairing corroded structure in accordance with 
service bulletin, the repair of any corrosion shall be done in 
accordance with a method approved by the Manager, New York Aircraft 
Certification Office (ACO), FAA, Engine and Propeller Directorate.
    (2) If any black film insulation is detected, prior to further 
flight, perform the follow-on actions in accordance with the service 
bulletin. (The follow-on actions include removal of any black film 
insulation, an inspection to detect corrosion, repair of any 
corroded structure, and installation of new silver blankets.) 
However, in lieu of repairing corroded structure in accordance with 
service bulletin, the repair of any corrosion shall be done in 
accordance with a method approved by the Manager, New York ACO.
    (d) As of the effective date of this AD, no person shall install 
black Orcon film insulation, part number AN46B/AN36B, on any 
airplane.
    (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, New York 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.

    (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.

    Issued in Renton, Washington, on September 23, 1996.
Darrell M. Pederson,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 96-24890 Filed 9-27-96; 8:45 am]
BILLING CODE 4910-13-U