01-27068. Airworthiness Directives; Bombardier Model CL-600-2B19 Series Airplanes

AGENCY:

Federal Aviation Administration, DOT.

ACTION:

Final rule.

SUMMARY:

This amendment adopts a new airworthiness directive (AD), applicable to certain Bombardier Model CL-600-2B19 series airplanes, that requires repetitive eddy current inspections for cracking of the main landing gear (MLG) main fittings, and replacement with a new or serviceable MLG, if necessary. This action also requires servicing the MLG shock struts; inspecting the MLG shock struts for nitrogen pressure, visible chrome dimension, and oil leakage; and performing corrective actions, if necessary. The actions specified by this AD are intended to prevent failure of the MLG main fitting, which could result in collapse of the MLG upon landing. This action is intended to address the identified unsafe condition.

DATES:

Effective December 4, 2001.

The incorporation by reference of certain publications listed in the regulations is approved by the Director of the Federal Register as of December 4, 2001.

ADDRESSES:

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, 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:

Serge Napoleon, Aerospace Engineer, ANE-171, FAA, New York Aircraft Certification Office, 10 Fifth Street, Third Floor, Valley Stream, New York 11581; telephone [phone]; fax [phone].

SUPPLEMENTARY INFORMATION:

A proposal to amend part 39 of the Federal Aviation Regulations (14 CFR part 39) to include an airworthiness directive (AD) that is applicable to certain Bombardier Model CL-600-2B19 series airplanes was published as a supplemental notice of proposed rulemaking (NPRM) in the Federal Register on March 23, 2001 (66 FR 16156). That action proposed to require repetitive eddy current inspections for cracking of the main landing gear (MLG) main fittings, and replacement with a new or serviceable MLG, if necessary. That action also proposed to require servicing the MLG shock struts; inspecting the MLG shock struts for nitrogen pressure, visible chrome dimension, and oil leakage; and performing corrective actions, if necessary.

Public Comment

Interested persons have been afforded an opportunity to participate in the making of this amendment. Due consideration has been given to the comments received.

Request To Revise the Applicability

One commenter points out that the inspection specified in paragraph (a) of the NPRM requires compliance with Part “B” of Bombardier Alert Service Bulletin A601R-32-079, dated December 1, 2000; however, Appendix 1 of that alert service bulletin states that the inspection is necessary only for MLG main fittings having part numbers (P/Ns) 17064-101, 17064-102, 17064-103, and 17064-104, not to all airplanes having serial numbers 7003 and subsequent. The commenter explains that airplanes currently being delivered have MLG main fittings having P/Ns 17064-105 and 17064-106. The FAA infers that the commenter is requesting that we revise the applicability of the final rule.

The FAA agrees with the commenter. We have verified with Transport Canada Civil Aviation (TCCA), which is the airworthiness authority for Canada, that airplanes having MLG main fittings having P/Ns 17064-105 and 17064-106 are not subject to the requirements of this final rule. Therefore, we have revised the applicability of the final rule to clarify that the final rule applies to Bombardier Model CL-600-2B19 series airplanes, certificated in any category, having serial number 7003 and subsequent, and equipped with a MLG main fitting having P/N 17064-101, 17064-102, 17064-103, or 17064-104.

Requests To Withdraw the NPRM

1. One commenter requests that the NPRM be withdrawn. The commenter states that, since the reason for the NPRM was one event of a misserviced strut by a foreign air carrier, it is not necessary to issue an AD. In addition, the commenter suggests that requiring repetitive strut servicing could be done by mandating that the strut inspection be added to the operators' inspection programs. The commenter contends that incorporating such inspection requirements into the inspection program is preferred by operators.

2. Another commenter states that it has conducted 1,496 eddy current inspections in accordance with the alert service bulletin referenced in the NPRM and has found no discrepancies. This same commenter also states that it has been servicing the shock struts beyond the requirements specified in paragraph (b) of the NPRM by performing a complete reservicing of the shock strut with oil and nitrogen every 12 months. The FAA infers that the commenter is requesting that the NPRM be withdrawn.

3. Another commenter suggests that an annual complete reservicing of the MLG shock strut performed in conjunction with an annual eddy current inspection is an equivalent or better level of safety than the actions proposed in the NPRM. The commenter notes that the brake lines are clamped to the MLG main fittings and must be moved or removed to gain access to the inspection area. Therefore, the commenter asserts that its proposed actions would have the benefit of reducing the adverse affects on reliability and safety impact caused by frequent disturbance of the brake lines.

The FAA does not concur that the NPRM should be withdrawn for the following reasons:

1. TCCA, has advised us that three cases of premature failures of the MLG have been reported. Because implementation and quality of various existing maintenance programs may differ, we have determined that by issuing an AD to require eddy current inspections for cracks and replacement, if necessary, with a new or serviceable fitting, (and, as required by paragraph (b) of this AD, servicing and inspecting the MLG shock struts to determine the nitrogen pressure, visible chrome dimension and any oil leakage), the identified unsafe condition will be addressed appropriately.

2. In requiring the actions specified in this final rule, the FAA has not precluded an operator's prerogative to perform additional actions to further increase the safety level that an operator may wish to take. As stated previously, we acknowledge that some operators' maintenance programs may be of a higher quality than others. However, our obligation remains to issue an AD to address the identified unsafe condition; and the rule must apply to everyone to ensure that all affected airplanes are covered, regardless of who operates them. However, under the provisions of paragraph (g) of the final rule, we may approve requests for an alternate method of compliance if data are submitted to substantiate that such a method would provide an acceptable level of safety.

3. The FAA does not agree that an annual complete reservicing of the MLG shock strut performed in conjunction with an annual eddy current inspection is equivalent to or a better level of safety than the actions required by this final rule. Since the airplane model accumulates an average of approximately 2,500 flight cycles per year, that would require the eddy current inspection only every 2,500 flight cycles. However, according to the investigation that was conducted by the original equipment manufacturer (OEM), it took only 2,000 flight cycles for the cracking to develop from initiation to critical size. Therefore, we have determined that it is necessary to require inspections at intervals not to exceed 500 flight cycles.

As to the adverse affects on the reliability and safety impact caused by frequent disturbance of the brake lines, we point out that the inspection and its repetitive interval are not only consistent with the OEM service bulletin, but also include specific procedures for handling the brake lines with minimal disturbance. No change is necessary to the final rule regarding these requests.

Requests To Remove Certain Paragraphs of the NPRM

Two commenters state that the requirements of paragraphs (c) and (d) of the NPRM are unnecessary. One commenter states that paragraphs (c) and (d) of the NPRM, which require “inspection of shock strut servicing,” per Bombardier Alert Service Bulletin A601R-32-079, are already incorporated into the Maintenance Review Board (MRB) document, Task 32-00-00-09 (100 flight hours/routine check) and Task 32-00-00-11 (400 flight hours/A check). The FAA infers that the commenters are requesting that paragraphs (c) and (d) of the NPRM be removed.

The FAA does not agree. Although the inspection and servicing of the shock struts required by paragraphs (c) and (d) of the final rule may be the same as the MRB document, our obligation remains to issue an AD to address the identified unsafe condition. However, under the provisions of paragraph (g) of the final rule, we may approve requests for an alternate method of compliance if data are submitted to substantiate that such a method would provide an acceptable level of safety.

One of those commenters also notes that paragraph (e) of the NPRM “requires extension of repetitive inspection.” The commenter states that, based on the results of 1,496 negative eddy current inspections, and the fact that the inspections are incorporated into the MRB document, paragraph (e) of the NPRM is not necessary.

The FAA does not concur that paragraph (e) of the NPRM is unnecessary. We point out that in paragraph (e) of this final rule, the extension of the inspection interval from every 500 flight cycles to every 1,000 flight cycles is not “required,” but “may” be extended if the conditions specified in paragraph (e) of the final rule are met. In accordance with the provisions of that paragraph, if an operator does not wish to extend the repetitive inspection interval, there is no requirement to do so.

Requests To Revise the Requirements of Paragraph (a) of the NPRM

One commenter requests that paragraph (a) of the NPRM be revised to add the visual inspection that is specified in the alert service bulletin, which is referenced as the source of service information in the NPRM. The commenter notes that the alert service bulletin only specifies an eddy current inspection if cracking is detected during the visual inspection. This same commenter also requests that paragraph (a) of the NPRM be revised to reflect a compliance threshold of 1,000 hours with escalation to a “C” check (currently 4,000 flight hours for that operator's operations).

The FAA does not agree with either of the commenter's requests. The three instances of premature failures of the MLG main fittings indicates that the crack propagation is rapid in high-strength steel material. In fact, investigation into those three failure cases revealed that the crack growth from initiation to critical crack size was about 2,000 flight cycles. Since eddy current inspections are more reliable in detecting such rapid crack growth, we find that the repetitive inspection interval of 500 flight cycles required by paragraph (a) of the final rule to be appropriate.

Requests To Extend the Repetitive Inspection Intervals

Two commenters request that the repetitive inspection interval of 500 flight cycles specified in paragraph (a) of the NPRM be extended. One commenter asks that the repetitive inspection interval be revised to require the inspection every “C” check. This commenter justifies an extension of the repetitive inspections based on the fact that it has already accomplished three consecutive inspections (500 flight cycles) per the Bombardier alert service bulletin specified in the NPRM, and has found no defects. The commenter states that the current maintenance program effectively prevents improper servicing. The other commenter requests that the repetitive inspection interval be extended to every “C” check after a reasonable number of non-destructive testing (NDT) inspections (perhaps two) are done at the 1,000 flight cycle interval. Both commenters state that, since they are aware of only one cracking occurrence, there is no proof that there is an inherent flaw in the MLG main fitting.

The FAA does not concur that the repetitive inspection interval may be extended. We stated previously that TCCA has advised us that three cases of premature failures of the MLG have been reported. In addition, we also stated previously that the repetitive inspection interval was based on the findings of the investigation into the rapid crack growth that occurred on the MLG main fittings. No change to the final rule in this regard is necessary. However, under the provisions of paragraph (g) of the final rule, we may approve requests for adjustments to the compliance time if data are submitted to substantiate that such an adjustment would provide an acceptable level of safety.

Interim Action

This is considered to be interim action until final action is identified, at which time the FAA may consider additional rulemaking.

Conclusion

After careful review of the available data, including the comments noted above, the FAA has determined that air safety and the public interest require the adoption of the rule with the change described previously. The FAA has determined that this change will neither increase the economic burden on any operator nor increase the scope of the AD.

Cost Impact

There are approximately 339 Bombardier Model CL-600-2B19 series airplanes of the affected design in the worldwide fleet. The FAA estimates that 236 airplanes of U.S. registry will be affected by this proposed AD, that it will take approximately 3 work hours per airplane to accomplish an eddy current inspection, and the servicing actions, and inspections specified in paragraphs (a), (b), and (c) of this AD. We estimate that the average labor rate is $60 per work hour. Based on these figures, the cost impact of this AD on U.S. operators is estimated to be $42,480, or $180 per airplane.

The 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 cost impact figures discussed in AD rulemaking actions represent only the time necessary to perform the specific actions actually required by the AD. These figures typically do not include incidental costs, such as the time required to gain access and close up, planning time, or time necessitated by other administrative actions.

Regulatory Impact

The regulations adopted herein will not have a substantial direct effect 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, it is determined that this final rule does not have federalism implications under Executive Order 13132.

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 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.

§ 39.13

[Amended]

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

2001-22-09 Bombardier, Inc. (Formerly Canadair): Amendment 39-12488. Docket 2000-NM-68-AD.

Applicability: Model CL-200-2B19 series airplanes, certificated in any category, having serial numbers 7003 and subsequent, and equipped with a main landing gear (MLG) main fitting having part number (P/N) 17064-101, 17064-102, 17064-103, or 17064-104.

Note 1:

This AD applies to each airplane identified in the preceding applicability provision, regardless of whether it has been 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 (g) 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 prevent failure of MLG main fitting, which could result in collapse of the MLG upon landing, accomplish the following:

Inspection and Replacement

(a) Prior to the accumulation of 1,500 total flight cycles, or within 150 flight cycles after the effective date of this AD, whichever occurs later: Perform an eddy current inspection to detect cracking of the MLG main fittings, in accordance with Part B of the Accomplishment Instructions of Bombardier Alert Service Bulletin A601R-32-079, Revision D, dated December 1, 2000. If any cracking is found, prior to further flight, replace the cracked fitting with a new or serviceable fitting in accordance with the alert service bulletin. Repeat the inspection thereafter at intervals not to exceed 500 flight cycles.

Servicing the Shock Struts

(b) Prior to the accumulation of 1,500 total flight cycles since the date of manufacture, or within 500 flight cycles after the effective date of this AD, whichever occurs later: Perform a servicing (Oil and Nitrogen) of the MLG shock struts (left and right main landing shock struts), in accordance with Part C (for airplanes on the ground) or Part D (for airplanes on jacks) of the Accomplishment Instructions of Bombardier Alert Service Bulletin A601R-32-079, Revision D, dated December 1, 2000.

Other Inspections

(c) Within 500 flight cycles after completing the actions required by paragraph (b) of this AD: Perform an inspection of the MLG left and right shock struts for nitrogen pressure, visible chrome dimension, and oil leakage, in accordance with Part E of the Accomplishment Instructions of Bombardier Alert Service Bulletin A601R-32-079, Revision D, dated December 1, 2000. Thereafter, repeat the inspection at intervals not to exceed 500 flight cycles.

Corrective Actions for Certain Inspections

(d) If the chrome extension dimension of the shock strut pressure reading is outside the limits specified in the Airplane Maintenance Manual, Task 32-11-05-220-801, or any oil leakage is found: Prior to further flight, service the MLG shock strut in accordance with Part C (for airplanes on the ground) or Part D (for airplanes on jacks) of the Accomplishment Instructions of Bombardier Alert Service Bulletin A601R-32-079, Revision D, dated December 1, 2000.

Extension of the Repetitive Interval

(e) After the effective date of this AD: After a total of five consecutive inspections of the MLG shock struts that verify that the shock struts are serviced properly, and a total of five consecutive eddy current inspections of the MLG main fitting has been accomplished that verify there is no cracking of the main fitting, in accordance with Bombardier Alert Service Bulletin A601R-32-079, Revision D, dated December 1, 2000, the repetitive interval for the eddy current inspections required by paragraph (a) of this AD may be extended from every 500 flight cycles to every 1,000 flight cycles.

Reporting Requirement

(f) Within 30 days after each inspection and servicing required by paragraphs (a), (b), and (c) of this AD, report all findings, positive or negative, to: Bombardier Aerospace, Regional Aircraft, CRJ Action Desk, fax number 514-855-8501. Information collection requirements contained in this regulation have been approved by the Office of Management and Budget (OMB) under the provisions of the Paperwork Reduction Act of 1980 (44 U.S.C. 3501 et seq.) and have been assigned OMB Control Number 2120-0056.

Alternative Methods of Compliance

(g) 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. 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.

Special Flight Permits

(h) 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.

Incorporation by Reference

(i) The actions shall be done in accordance with Bombardier Alert Service Bulletin A601R-32-079, Revision D, dated December 1, 2000. 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, 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-1999-32R1, dated January 22, 2001.

Effective Date

(j) This amendment becomes effective on December 4, 2001.

Issued in Renton, Washington, on October 22, 2001.

Ali Bahrami,

Acting Manager, Transport Airplane Directorate, Aircraft Certification Service.