[Federal Register Volume 62, Number 222 (Tuesday, November 18, 1997)]
[Rules and Regulations]
[Pages 61436-61438]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 97-30104]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 97-NM-285-AD; Amendment 39-10209; AD 97-24-02]
RIN 2120-AA64


Airworthiness Directives; Bombardier Model CL-600-1A11, -2A12, 
and -2B16 Series Airplanes

AGENCY: Federal Aviation Administration, DOT.

ACTION: Final rule; request for comments.

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SUMMARY: This amendment adopts a new airworthiness directive (AD) that 
is applicable to certain Bombardier Model CL-600-1A11, -2A12, and -2B16 
series airplanes. This action requires repetitive inspections to detect 
cracks of a certain bulkhead web of the fuselage at certain locations, 
and repair, if necessary. This amendment is prompted by issuance of 
mandatory continuing airworthiness information by a foreign civil 
airworthiness authority. The actions specified in this AD are intended 
to detect and correct cracking in the pressure bulkhead at frame 
station (FS) 409.00, which could result in uncontrolled 
depressurization of the airplane and/or reduced structural integrity of 
the fuselage.

DATES: Effective December 3, 1997.
    The incorporation by reference of certain publications listed in 
the regulations is approved by the Director of the Federal Register as 
of December 3, 1997.
    Comments for inclusion in the Rules Docket must be received on or 
before December 18, 1997.

ADDRESSES: Submit comments in triplicate to the Federal Aviation 
Administration (FAA), Transport Airplane Directorate, ANM-103, 
Attention: Rules Docket No. 97-NM-285-AD, 1601 Lind Avenue, SW., 
Renton, Washington 98055-4056.
    The service information referenced in this AD may be obtained from 
Bombardier, Inc., Canadair, Aerospace Group, P.O. Box 6087, Station 
Centreville, Montreal, Quebec H3C 3G9, Canada. This information may be 
examined 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, 10 Fifth Street, 
Third Floor, 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: Franco Pieri, Aerospace Engineer, 
Airframe and Propulsion Branch, ANE-171, FAA, Engine and Propeller 
Directorate, New York Aircraft Certification Office, 10 Fifth Street, 
Third Floor, Valley Stream, New York 11581; telephone (516) 256-7526; 
fax (516) 568-2716.

SUPPLEMENTARY INFORMATION: Transport Canada Aviation (TCA), which is 
the airworthiness authority for Canada, recently notified the FAA that 
an unsafe condition may exist on certain Bombardier Model CL-600-1A11, 
-2A12, and -2B16 series airplanes. TCA advises that the structural 
configuration of these airplanes at frame station (FS) 409.00 is 
similar to that of Bombardier Model CL-600-2B19 (Regional Jet Series 
100 and 200) series airplanes, which was shown to have a pressurization 
problem caused by fatigue cracking in the underfloor pressure bulkhead 
of the fuselage. TCA has received several reports of cracking at this 
same location on Bombardier Model CL-600-1A11, -2A12, and -2B16 series 
airplanes. This condition, if not corrected, could result in 
uncontrolled depressurization of the airplane and/or reduced structural 
integrity of the fuselage.

Other Relevant Rules

    The FAA previously issued AD 97-14-11, amendment 39-10082 (62 FR 
38206, July 17, 1997), which requires repetitive inspections to detect 
cracks of a certain bulkhead web of the fuselage at certain locations, 
and repair, if necessary. That AD applies to certain Bombardier Model 
CL-600-2B19 (Regional Jet Series 100 and 200) series airplanes.

Explanation of Relevant Service Information

    The manufacturer has issued Canadair Challenger Service Bulletin 
601-0501, dated September 12, 1997 [for Model CL-600-2A12 (CL-601) and 
CL-600-2B16 (CL-601-3A/-3R) series airplanes]; Service Bulletin 604-53-
007, dated September 30, 1997 [for Model CL-600-2B16 (CL-604) series 
airplanes]; and Service Bulletin 600-0679, dated September 12, 1997 
[for Model CL-600-1A11 (CL-600) series airplanes]. These service 
bulletins describe procedures for repetitive detailed visual 
inspections to detect fatigue cracking of the underfloor pressure 
bulkhead at FS 409.00, and repair, if necessary. TCA classified these 
service bulletins as mandatory and issued Canadian airworthiness 
directive CF-97-16, dated September 25, 1997, in order to assure the 
continued airworthiness of these airplanes in Canada.

FAA's Conclusions

    These airplane models are manufactured in Canada and are 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, TCA has kept the FAA informed of the 
situation described above. The FAA has examined the findings of TCA, 
reviewed all available information, and determined that AD action is 
necessary for products of this type design that are

[[Page 61437]]

certificated for operation in the United States.

Explanation of Requirements of Rule

    Since an unsafe condition has been identified that is likely to 
exist or develop on other airplanes of the same type design registered 
in the United States, this AD requires accomplishment of the 
inspections specified in the service bulletins described previously. In 
addition, this AD requires repair, if necessary, in accordance with a 
method approved by the FAA.
    Operators should note that, while it is not the FAA's normal policy 
to allow flight with known cracks, this AD does permit further flight 
with cracking within certain limits. The results of a review, conducted 
by the manufacturer, revealed that cracking in the underfloor pressure 
bulkhead of the fuselage will not result in rapid decompression of the 
airplane. Therefore, according to the review, if the crack size limits 
are strictly observed and if repetitive inspections are performed at 
the required intervals, cracks that grow beyond the limits will be 
detected, and corrective action taken, before they can grow to a size 
that would create an unacceptable risk of structural failure. Transport 
Canada Aviation concurs with the findings of this review. In 
consideration of these findings and based on the FAA's criteria for 
flight with known cracking, the FAA has determined that further flight 
with cracking within certain limits in the center pressure bulkhead is 
permissible for an interim period.
    This is considered to be interim action. The manufacturer has 
advised that it currently is developing a modification that will 
positively address the unsafe condition addressed by this AD. Once this 
modification is developed, approved, and available, the FAA may 
consider additional rulemaking.

Determination of Rule's Effective Date

    Since a situation exists that requires the immediate adoption of 
this regulation, it is found that notice and opportunity for prior 
public comment hereon are impracticable, and that good cause exists for 
making this amendment effective in less than 15 days.

Comments Invited

    Although this action is in the form of a final rule that involves 
requirements affecting flight safety and, thus, was not preceded by 
notice and an opportunity for public comment, comments are invited on 
this rule. Interested persons are invited to comment on this 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 under the caption ADDRESSES. All 
communications received on or before the closing date for comments will 
be considered, and this rule may be amended in light of the comments 
received. Factual information that supports the commenter's ideas and 
suggestions is extremely helpful in evaluating the effectiveness of the 
AD action and determining whether additional rulemaking action would be 
needed.
    Comments are specifically invited on the overall regulatory, 
economic, environmental, and energy aspects of the rule that might 
suggest a need to modify the 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 that 
summarizes each FAA-public contact concerned with the substance of this 
AD will be filed in the Rules Docket.
    Commenters wishing the FAA to acknowledge receipt of their comments 
submitted in response to this rule must submit a self-addressed, 
stamped postcard on which the following statement is made: ``Comments 
to Docket Number 97-NM-285-AD.'' The postcard will be date stamped and 
returned to the commenter.

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.
    The FAA has determined that this regulation is an emergency 
regulation that must be issued immediately to correct an unsafe 
condition in aircraft, and that it is not a ``significant regulatory 
action'' under Executive Order 12866. It has been determined further 
that this action involves an emergency regulation under DOT Regulatory 
Policies and Procedures (44 FR 11034, February 26, 1979). If it is 
determined that this emergency regulation otherwise would be 
significant under DOT Regulatory Policies and Procedures, a final 
regulatory evaluation will be prepared and placed in the Rules Docket. 
A copy of it, if filed, 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:

97-24-02  Bombardier, Inc.: Amendment 39-10209. Docket 97-NM-285-AD.

    Applicability: Model CL-600-1A11 (CL-600) series airplanes, 
serial numbers 1004 through 1085 inclusive; Model CL-600-2A12 (CL-
601) series airplanes, serial numbers 3001 through 3066 inclusive; 
Model CL-600-2B16 (CL-601-3A/-3R) series airplanes, serial numbers 
5001 through 5194 inclusive; Model CL-600-2B16 (CL-604) series 
airplanes, serial numbers 5301 through 5352 inclusive; 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 request approval for an 
alternative method of compliance in 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 detect and correct fatigue cracking in the underfloor 
pressure bulkhead of the fuselage, which could result in 
uncontrolled depressurization of the airplane and/or reduced 
structural integrity of the fuselage, accomplish the following:
    (a) For Model CL-600-1A11 (CL-600) airplanes: Prior to the 
accumulation of 1,900 total landings, or within 100 landings after 
the effective date of this AD, whichever occurs later, perform a 
detailed visual inspection to detect cracks at frame station (FS) 
409 of the bulkhead web [part number (P/N) 600-32014-71/-95/-105], 
in accordance with Canadair Challenger Service

[[Page 61438]]

Bulletin 600-0679, dated September 12, 1997.
    (1) If no crack is detected, repeat the detailed visual 
inspection thereafter at intervals not to exceed 600 landings.
    (2) If any crack is detected and if all three of the conditions 
specified in paragraphs (a)(2)(i), (a)(2)(ii), and (a)(2)(iii) of 
this AD are met, within 600 landings or 12 months after the crack is 
detected, whichever occurs first, repair the cracking in accordance 
with a method approved by the Manager, New York Aircraft 
Certification Office (ACO), FAA, Engine and Propeller Directorate. 
Until the repair is accomplished, repeat the detailed visual 
inspection at intervals not to exceed 100 landings.
    (i) No more than one crack exists at each corner radius, as 
specified in the service bulletin; and
    (ii) No crack extends under the angles having P/N 600-32014-13 
and P/N 600-32014-15 on the aft side of the bulkhead web; and
    (iii) No crack exists in angles having P/N 600-32014-13 and P/N 
600-32014-15 on the aft side of the bulkhead web.
    (3) If any cracking other than that identified in paragraph 
(a)(2) of this AD is detected, prior to further flight, repair it in 
accordance with a method approved by the Manager, New York ACO.
    (b) For Model CL-600-2A12 (CL-601), CL-600-2B16 (CL-601-3A/-3R), 
and CL-600-2B16 (CL-604) series airplanes: Prior to the accumulation 
of 1,100 total landings, or within 100 landings after the effective 
date of this AD, whichever occurs later, perform a detailed visual 
inspection to detect cracks at FS 409 of the bulkhead web (P/N 600-
32014-105/-137), in accordance with Canadair Challenger Service 
Bulletin 601-0501, dated September 12, 1997 [for Model CL-600-2A12 
(CL-601) and CL-600-2B16 (CL-601-3A/-3R) series airplanes); or 
Canadair Challenger Service Bulletin 604-53-007, dated September 30, 
1997 [for Model CL-600-2B16 (CL-604) series airplanes]; as 
applicable.
    (1) If no crack is detected, repeat the detailed visual 
inspection thereafter at intervals not to exceed 600 landings.
    (2) If any crack is detected and if all three of the conditions 
specified in paragraphs (b)(2)(i), (b)(2)(ii), and (b)(2)(iii) of 
this AD are met, within 600 landings or 12 months after the crack is 
detected, whichever occurs first, repair the cracking in accordance 
with a method approved by the Manager, New York ACO. Until the 
repair is accomplished, repeat the detailed visual inspection at 
intervals not to exceed 100 landings.
    (i) No more than one crack exists at each corner radius, as 
specified in the service bulletin; and
    (ii) No crack extends under the angles having P/N 600-32014-113 
and P/N 600-32014-115 on the aft side of the bulkhead web; and
    (iii) No crack exists in angles having P/N 600-32014-113 and P/N 
600-32014-115 on the aft side of the bulkhead web.
    (3) If any cracking other than that identified in paragraph 
(b)(2) of this AD is detected, prior to further flight, repair it in 
accordance with a method approved by the Manager, New York ACO.
    (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. 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.

    (d) 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.
    (e) The inspections shall be done in accordance with Canadair 
Challenger Service Bulletin 600-0679, dated September 12, 1997; 
Canadair Challenger Service Bulletin 601-0501, dated September 12, 
1997; or Canadair Challenger Service Bulletin 604-53-007, dated 
September 30, 1997; 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 
Bombardier, Inc., Canadair, Aerospace Group, P.O. Box 6087, Station 
Centre-ville, Montreal, Quebec H3C 3G9, 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, 10 Fifth 
Street, Third Floor, Valley Stream, New York; or at the Office of 
the Federal Register, 800 North Capitol Street, NW., suite 700, 
Washington, DC.

    Note 3: The subject of this AD is addressed in Canadian 
airworthiness directive CF-97-16, dated September 25, 1997.

    (f) This amendment becomes effective on December 3, 1997.

    Issued in Renton, Washington, on November 10, 1997.
Darrell M. Pederson,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 97-30104 Filed 11-17-97; 8:45 am]
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