Airworthiness Directives; Bombardier Model CL-600-2B19 (Regional Jet Series 100) Series Airplanes

DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 98-NM-192-AD]

RIN 2120-AA64

Airworthiness Directives; Bombardier Model CL-600-2B19 (Regional

Jet Series 100) Series Airplanes

AGENCY: Federal Aviation Administration, DOT.

ACTION: Notice of proposed rulemaking (NPRM).

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SUMMARY: This document proposes the supersedure of an existing

airworthiness directive (AD), applicable to certain Bombardier Model

CL-600-2B19 (Regional Jet Series 100 and 200) series airplanes, that

currently requires repetitive inspections to detect cracks of a certain

bulkhead web of the fuselage at certain locations, and repair, if

necessary. This action would revise the repetitive inspection intervals

for certain airplanes, and would require modification or repair, as

applicable. This proposal is prompted by the development of a

modification that will adequately address the identified unsafe

condition. The actions specified by the proposed AD are intended to

detect and correct fatigue cracking, which could result in uncontrolled

depressurization of the airplane and/or reduced structural integrity of

the fuselage.

DATES: Comments must be received by December 9, 1999.

ADDRESSES: Submit comments in triplicate to the Federal Aviation

Administration (FAA), Transport Airplane Directorate, ANM-114,

Attention: Rules Docket No. 98-NM-192-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., Canadair, Aerospace Group, P.O. Box

6087, Station Centre-ville, 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.

FOR FURTHER INFORMATION CONTACT: George Duckett, 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) 256-7525;

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 98-NM-192-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-114, Attention: Rules

Docket No. 98-NM-192-AD, 1601 Lind Avenue, SW., Renton, Washington

98055-4056.

Discussion

On July 11, 1997, the FAA issued AD 97-14-11, amendment 39-10082

(62 FR 38206, July 17, 1997), applicable to certain Bombardier Model

CL-600-2B19 (Regional Jet Series 100 and 200) series airplanes, to

require repetitive inspections to detect cracks of a certain bulkhead

web of the fuselage at certain locations, and repair, if necessary.

That action was prompted by a report of a pressurization problem during

flight, which was caused by fatigue cracking in the underfloor pressure

bulkhead of the fuselage. The requirements of that AD are intended to

detect and correct such fatigue cracking, which could result in

uncontrolled depressurization of the airplane and/or reduced structural

integrity of the fuselage.

Actions Since Issuance of Previous Rule

In the preamble of AD 97-14-11, the FAA indicated that the actions

required by that AD were considered ``interim action'' and that further

rulemaking action was being considered to require modification of the

affected fuselage frames once new service information was available.

The manufacturer has now released such information, and the FAA has

determined that further rulemaking is indeed necessary; this proposed

AD follows from that determination.

Issuance of New Service Information

The manufacturer has issued Canadair Regional Jet Alert Service

Bulletin A601R-53-045, Revision `D,' including Appendix 1, dated

December 22, 1997, which describes procedures for repetitive detailed

inspections to detect cracks of a certain bulkhead web of the fuselage

at certain locations; and follow-on corrective actions, if necessary.

The

[[Page 61040]]

inspections also involve determining whether a crack located at the

pressure bulkhead of frame station (FS)409+128 is within certain limits

specified in the alert service bulletin.

In the event that a crack is determined to be outside the limits

specified in Part A of the Accomplishment Instructions of the alert

service bulletin, the follow-on corrective actions would include a high

frequency eddy current (HFEC) inspection of the forward side of the

web, to detect cracks of fuselage FS409+128 bulkhead web along the

upper edge of the horizontal angle. As listed in Part A of paragraph

2.B. of the Accomplishment Instructions, airplanes may be returned to

service provided that any cracking detected is within certain limits

specified in the alert service bulletin.

The manufacturer also has issued Canadair Regional Jet Service

Bulletin 601R-53-046, Revision `B,' dated December 22, 1997, which

describes procedures for repair of the pressure bulkhead at FS409+128.

The manufacturer also has issued Canadair Regional Jet Service

Bulletin 601R-53-047, Revision `D,' including Appendix 1 and Appendix

2, dated December 22, 1997, describes procedures for modification of

the affected areas of the pressure bulkhead at FS409+128. This

modification is only applicable to those airplanes that have been

inspected and are found to be free of cracks. The modification involves

the installation of reinforcement components for the pressure bulkhead

at FS409+128.

Accomplishment of the actions specified in the service bulletins is

intended to adequately address the identified unsafe condition.

Transport Canada Civil Aviation (TCCA) classified Canadair Regional Jet

Service Bulletins A601R-53-045 and 601R-53-046 as mandatory, but did

not classify Service Bulletin 601R-53-047 as mandatory, and issued

Canadian airworthiness directive CF-97-11R2, dated December 22, 1997,

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

Sec. 21.29 of the Federal Aviation Regulations (14 CFR 21.29) and the

applicable bilateral airworthiness agreement. Pursuant to this

bilateral airworthiness agreement, TCCA has kept the FAA informed of

the situation described above. The FAA has examined the findings of

TCCA, 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 registered

in the United States, the proposed AD would supersede AD 97-14-11 to

continue to require repetitive inspections to detect cracks of a

certain bulkhead web of the fuselage at certain locations. This

proposed AD would revise the repetitive inspection intervals for

certain airplanes, and would require modification or repair, as

applicable. Accomplishment of the modification or repair would

terminate the requirements of this proposed AD. Certain actions would

be required to be accomplished in accordance with the service bulletins

described previously.

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 Civil 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.

Differences Between Proposed Rule and Service Bulletin

Operators should note that the Canadair Regional Jet Alert Service

Bulletin A601R-53-045, Revision `D,' including Appendix 1, dated

December 22, 1997, recommends that the initial inspection be performed

no later than 10 flight hours after the alert service bulletin date of

issuance. This proposed AD would increase the initial inspection

threshold to require the initial inspection be performed within 20

flight hours after the effective date of this AD. In developing an

appropriate initial inspection compliance time for this AD, the FAA

considered not only the manufacturer's recommendation, but also the

degree of urgency associated with addressing the subject unsafe

condition. In light of these factors, the FAA finds a compliance time

of 20 flight hours for initiating the required actions to be warranted,

in that it represents an appropriate interval of time allowable for

affected airplanes to continue to operate without compromising safety.

Operators also should note that, although the Canadair Regional Jet

Service Bulletins A601R-53-045, Revision `D,' and 601R-53-046, Revision

`B,' specify that the manufacturer may be contacted for disposition of

certain cracking conditions, this proposal would require the repair of

those conditions to be accomplished in accordance with a method

approved by the FAA.

Differences Between Proposed Rule and Foreign Airworthiness

Directive

The proposed AD would differ from the parallel Canadian

airworthiness directive in that it would require accomplishment of the

modification described in Canadair Regional Jet Service Bulletin 601R-

53-047, Revision `D,' within 9 months after the effective date of this

AD. The parallel Canadian airworthiness directive recommends, but does

not require, the accomplishment of the modification. Additionally, in

the event that cracking within certain limits is found, this proposed

AD would require a repair to be accomplished within 6 months after the

effective date of this AD, or within 3 months after the initial date

the crack was detected, whichever occurs later. The Canadian

airworthiness directive specifies that the airplane may be returned to

service provided that re-inspections are accomplished at certain flight

hour intervals. The FAA has determined that, in this case long-term

continued operational safety will be adequately assured by

accomplishing the modification or repair to remove the source of the

problem, rather than by accomplishing repetitive inspections at certain

flight hour intervals.

Explanation of Applicability

The applicability of this proposed AD would affect Bombardier Model

CL-600-2B19 (Regional Jet Series 100) series airplanes, whereas the

previously issued AD 97-14-11 addressed Bombardier Model CL-600-2B19

(Regional Jet Series 100 and 200) series airplanes. The FAA

inadvertently referenced Bombardier Model CL-600-2B19 (Regional Jet

Series 200) series

[[Page 61041]]

airplanes in the previously issued AD. This airplane series is not type

certificated in the U.S.

Additionally, the applicability of this proposed AD excludes any

airplane on which Canadair Regional Jet Service Bulletins 601R-53-046,

Revision `B,' dated December 22, 1997, and 601R-53-047, Revision `D,'

including Appendix 1 and Appendix 2, dated December 22, 1997, has been

accomplished.

Cost Impact

There are approximately 77 airplanes of U.S. registry that would be

affected by this proposed AD.

The inspection that is currently required by AD 97-14-11 takes

approximately 2 work hours per airplane to accomplish, at an average

labor rate of $60 per work hour. Based on these figures, the cost

impact of the currently required inspection on U.S. operators is

estimated to be $9,960, or $120 per airplane, per inspection cycle.

The repair that is proposed in this AD action would take

approximately 300 work hours per airplane to accomplish, at an average

labor rate of $60 per work hour. Required parts would cost

approximately $1,828. Based on these figures, the cost impact of the

repair on U.S. operators is estimated to be $19,828 per airplane.

The modification that is proposed in this AD action would take

approximately 212 hours per airplane to accomplish, at an average labor

rate of $60 per work hour. Required parts would cost approximately

$935. Based on these figures, the cost impact of the modification on

U.S. operators is estimated to be $13,655 per airplane.

The cost impact figures discussed above are based on assumptions

that no operator has yet accomplished any of the current or proposed

requirements of this AD action, and that no operator would accomplish

those actions in the future if this AD were not adopted. However, the

FAA has been advised that the manufacturer has committed previously to

its customers that it will bear the labor costs associated with the

repair and modification associated with accomplishing the actions

required by this AD. Additionally, the manufacturer has indicated the

warranty remedies may be available to defer the cost of the replacement

parts also associated with accomplishing the actions required by this

proposed AD.

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 removing amendment 39-10082 (62 FR

38206, July 17, 1997), and by adding a new airworthiness directive

(AD), to read as follows:

Bombardier, Inc. (Formerly Canadair): Docket 98-NM-192-AD.

Supersedes AD 97-14-11, Amendment 39-10082.

Applicability: Model CL-600-2B19 (Regional Jet Series 100)

series airplanes, serial numbers 7003 through 7185 inclusive; except

those airplanes on which Canadair Regional Jet Service Bulletin

601R-53-046, Revision `B,' dated December 22, 1997, or 601R-53-047,

Revision `D,' including Appendix 1 and Appendix 2, dated December

22, 1997, has been accomplished; 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 (d)(1)

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:

Detailed Visual Inspections

(a) Perform a detailed visual inspection to detect cracks at

FS409+128 of the bulkhead web drawing number 601R32208-123 of the

fuselage, in accordance with Canadair Regional Jet Alert Service

Bulletin A601R-53-045, Revision `D,' including Appendix 1 and

Appendix 2, dated December 22, 1997, at the time specified in

paragraph (a)(1) or (a)(2) of this AD, as applicable, until

accomplishment of paragraph (b) or (c) of this AD, as applicable.

(1) For airplanes that have accomplished a detailed visual

inspection in accordance with AD 97-14-11 prior to the effective

date of this AD: Perform a subsequent detailed visual inspection

prior to the accumulation of 1,000 total flight hours, or within 100

flight hours after the immediately preceding inspection accomplished

in accordance with AD 97-14-11, whichever occurs later. Thereafter,

repeat the inspection at intervals not to exceed 100 flight hours.

(2) For airplanes that have not accomplished a detailed visual

inspection in accordance with AD 97-14-11 prior to the effective

date of this AD: Perform a detailed visual inspection within 20

flight hours after the effective date of this AD. Perform a

subsequent detailed visual inspection prior to the accumulation of

1,000 total flight hours, or within 100 flight hours after

accomplishment of the immediately preceding inspection, whichever

occurs later. Thereafter, repeat the inspection at intervals not to

exceed 100 flight hours.

Note 2: For the purposes of this AD, a detailed visual

inspection is defined as: ``An intensive visual examination of a

specific structural area, system, installation, or assembly to

detect damage, failure, or irregularity. Available lighting is

normally supplemented with a direct source of good lighting at

intensity deemed appropriate by the inspector. Inspection aids such

as mirror, magnifying lenses, etc. may be used. Surface cleaning and

elaborate access procedures may be required.''

Note 3: Accomplishment of the inspection required by paragraph

(a) of this AD, prior to the effective date of this AD in accordance

with Canadair Regional Jet Alert Service Bulletin A601R-53-045,

dated June 25, 1997; Revision `A,' including Appendix 1, dated June

26, 1997; Revision `B,' including Appendix 1, dated June 27, 1997;

or Revision

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`C,' including Appendix 1, dated July 2, 1997; is considered

acceptable for compliance with the applicable action specified by

this AD.

Modification

(b) For any airplane on which no cracking has been detected

during any inspection required by paragraph (a) of this AD: Within 9

months after the effective date of this AD, modify FS409+128 of the

bulkhead web drawing number 601R32208-123 of the fuselage in

accordance with Canadair Regional Jet Service Bulletin 601R-53-047,

including Appendix 1, Revision `D,' dated December 22, 1997.

Accomplishment of this modification terminates the requirements of

this AD.

Note 4: Any modification accomplished prior to the effective

date of this AD in accordance with Canadair Regional Jet Service

Bulletin 601R-53-047, including Appendix 1 and Appendix 2, dated

July 18, 1997; Revision `A,' including Appendix 1, dated July 31,

1997; Revision `B,' including Appendix 1, dated August 22, 1997; or

Revision `C,' including Appendix 1, dated October 7, 1997; is

considered acceptable for compliance with the applicable actions

required by this AD.

Repair

(c) For any airplane on which any cracking is detected during

any inspection required by paragraph (a) of this AD: Prior to

further flight, determine the extent of the cracking as specified in

Part A of paragraph 2.B. of the Accomplishment Instructions of

Canadair Regional Jet Alert Service Bulletin A601R-53-045, Revision

`D,' including Appendix 1, dated December 22, 1997, and accomplish

the requirements of paragraph (c)(1) or (c)(2), as applicable.

(1) If the cracking is within the limits specified by Part A of

paragraph 2.B. of the Accomplishment Instructions of the alert

service bulletin, accomplish the requirements of paragraphs

(c)(1)(i) and (c)(1)(ii) of this AD at the time specified in those

paragraphs.

(i) Repeat the detailed visual inspection required by paragraph

(a) of this AD thereafter at intervals not to exceed 100 flight

hours; and

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

within 3 months after the initial date the crack was detected,

whichever occurs later: Repair the affected area in accordance with

Canadair Regional Jet Service Bulletin 601R-53-046, Revision `B,'

dated December 22, 1997. Accomplishment of this repair terminates

the requirements of this AD.

Note 5: Any repair accomplished prior to the effective date of

this AD in accordance with Canadair Regional Jet Service Bulletin

601R-53-046, dated June 27, 1997, or Revision `A,' dated July 2,

1997, is considered acceptable for compliance with the applicable

actions specified by this AD.

(2) If the cracking is outside the limits specified by Part A of

the Accomplishment Instructions of the alert service bulletin, prior

to further flight, perform a high frequency eddy current (HFEC)

inspection to detect cracks of the forward side of the web of

fuselage FS409+128 bulkhead web drawing number 601R32208-123, along

the upper edge of the horizontal angle part number 601R32208-73, in

accordance with Part B of paragraph 2.B. of the Accomplishment

Instructions of the alert service bulletin.

(i) If, during any HFEC inspection required by paragraph (c)(2)

of this AD, any cracking is detected that is within the limits

specified by Part B of paragraph 2.B. of the Accomplishment

Instructions of the alert service bulletin, accomplish the

requirements of paragraphs (c)(2)(i)(A) and (c)(2)(i)(B) of this AD

at the times specified in those paragraphs.

(A) Repeat the HFEC inspection required by paragraph (c)(2) of

this AD thereafter at intervals not to exceed 50 flight hours, and

repeat the detailed visual inspection required by paragraph (a) of

this AD thereafter at interval not to exceed 100 flight hours; and

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

within 3 months after the initial date the crack was detected,

whichever occurs later: Repair the affected area in accordance with

Canadair Regional Jet Service Bulletin 601R-53-046, Revision `B,'

dated December 22, 1997. Accomplishment of this repair terminates

the requirements of this AD.

(ii) If, during any HFEC inspection required by paragraph (c)(2)

of this AD, any cracking is detected that is outside the limits

specified by Part B of paragraph 2.B. of the Accomplishment

Instructions of the alert service bulletin, prior to further flight,

determine the extent of the cracking as specified in paragraph 1.D.

(``Compliance'') of Canadair Regional Jet Service Bulletin 601R-53-

046, Revision `B,' dated December 22, 1997, and accomplish the

requirements of paragraph (c)(2)(ii)(A) or (c)(2)(ii)(B) of this AD,

as applicable.

(A) If the cracking is within the limits specified by paragraph

1.D. (``Compliance'') of the service bulletin, prior to further

flight, repair in accordance with the service bulletin.

Accomplishment of this repair terminates the requirements of this

AD.

(B) If the cracking is outside the limits specified by paragraph

1.D. (``Compliance'') of the service bulletin, prior to further

flight, repair in accordance with a method approved by the Manager,

New York Aircraft Certification Office (ACO).

Alternative Methods of Compliance

(d)(1) 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.

(d)(2) Alternative methods of compliance, approved previously in

accordance with AD 97-14-11, amendment 39-10082, are approved as

alternative methods of compliance for this AD.

Note 6: Information concerning the existence of approved

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

obtained from the New York ACO.

Special Flight Permits

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

Secs. 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.

Note 7: The subject of this AD is addressed in Canadian

airworthiness directive CF-97-11R2, dated December 22, 1997.

Issued in Renton, Washington, on November 2, 1999.

D.L. Riggin,

Acting Manager, Transport Airplane Directorate, Aircraft Certification

Service.

[FR Doc. 99-29177 Filed 11-8-99; 8:45 am]

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