Airworthiness Directives; Bombardier Model CL-600-2B19 (Regional Jet Series 100 & 440) Airplanes

DEPARTMENT OF TRANSPORTATION (DOT) Federal Aviation Administration (FAA)

Final rule.

CFR Part: "14 CFR Part 39"

RIN Number: "RIN 2120-AA64"

Citation: "73 FR 1964"

Document Number: "Docket No. FAA-2007-0047; Directorate Identifier 2007-NM-197-AD; Amendment 39-15329; AD 2008-01-04"

Page Number: "1964"

"Rules and Regulations"

SUMMARY: We are superseding an existing airworthiness directive (AD) for the products listed above. This AD results from mandatory continuing airworthiness information (MCAI) originated by an aviation authority of another country to identify and correct an unsafe condition on an aviation product. The MCAI describes the unsafe condition as:

   EFFECTIVE DATE: This AD becomes effective February 15, 2008.

   The Director of the Federal Register approved the incorporation by reference of certain publications listed in this AD as of September 5, 2007 (72 FR 46555, August 21, 2007).

   ADDRESSES: You may examine the AD docket on the Internet at http://www.regulations.gov or in person at the U.S. Department of Transportation, Docket Operations, M-30, West Building Ground Floor, Room W12-140, 1200 New Jersey Avenue, SE., Washington, DC.

   FOR FURTHER INFORMATION CONTACT: Dan Parrillo, Aerospace Engineer, Systems and Flight Test Branch, ANE-172, FAA, New York Aircraft Certification Office, 1600 Stewart Avenue, Suite 410, Westbury, New York 11590; telephone (516) 228-7305; fax (516) 794-5531.

   SUPPLEMENTARY INFORMATION:

Discussion

   We issued a notice of proposed rulemaking (NPRM) to amend 14 CFR part 39 to include an AD that would apply to the specified products. That NPRM was published in the Federal Register on October 17, 2007 (72 FR 58763) and proposed to supersede AD 2007-17-07, Amendment 39-15165 (72 FR 46555, August 21, 2007). That NPRM proposed to correct an unsafe condition for the specified products.

   That NPRM proposed to retain the requirements of AD 2007-17-07, i.e., revising the airplane flight manual (AFM) to incorporate Canadair Regional Jet Temporary Revision (TR) RJ/165, dated July 6, 2007, into the AFM; adding operational procedures into the AFM; training flight crewmembers and operational control/dispatch personnel on the operational procedures; and doing corrective "maintenance actions."

   That NPRM also proposed to require training flight crewmembers on reduced or zero flap landing, and doing additional corrective "maintenance actions" that include a pressure test of the flexible drive-shaft, and corrective actions if necessary. You may obtain further information by examining the MCAI in the AD docket.

Comments

   We gave the public the opportunity to participate in developing this AD. We considered the comments received.

Request To Exclude Certain Parts From Inspection

   Comair requests that we exclude from the proposed actions actuators with less than 2,000 flight hours since new or since repair as of July 12, 2007 (the issue date of Bombardier Service Bulletin 601R-27-150). Comair states that those actuators would not require the inspections of Part C of the Accomplishment Instructions of the service bulletin. Comair suggests that paragraph "(f)(3)" of the NPRM contain a statement qualifying under what conditions flap actuators must comply with Part C of the service bulletin by stating that new actuators, and those recently repaired where it can be shown that the inboard pinion shaft seals, part numbers (P/Ns) 853SC177-1/-2, were replaced, should be exempt from Part C (low temperature torque check test).

   We infer that Comair meant to refer to paragraph (g)(3) of the NPRM. We referred to Bombardier Service Bulletin 601R-27-150 as the appropriate source of service information for accomplishing the actions specified in paragraph (g)(3) of the NPRM. Paragraph (g)(3) of the NPRM proposes to require doing actions in accordance with Part C of the service bulletin. We agree that the actions specified in paragraph (g)(3) of this AD apply only to certain actuators as specified in paragraph 1.D., "Compliance," of the service bulletin. The actions in paragraph (g)(3) of this AD do not apply to new actuators with 2,000 or fewer flight hours and repaired actuators that have 2,000 or fewer flight hours since the pinion seals were changed. We have coordinated with TCCA, and we have revised paragraph (g)(3) of this AD to clarify which airplanes are subject to that paragraph.

Request To Remove Requirement Specified in Paragraph (g)(3) of the NPRM

   Mesaba Airlines requests that we remove the requirement proposed in paragraph (g)(3) of the NPRM to do a low temperature torque test of the flap actuators and all applicable corrective actions. Mesaba Airlines states that Bombardier and the flap actuator manufacturer (Eaton) are very close to certifying a new seal for the flap actuator. Mesaba Airlines explains that this new seal is intended to fix the internal fluid leakage issue in the actuator that could result in an actuator problem (and result in the actuator failing the low temperature torque test). Mesaba Airlines notes that once the modified flap actuator is certified, a fleet retrofit with the modified actuator would result in a more robust fix for the actuator issue.

   Mesaba Airlines further states that there is no guarantee currently that an actuator installed to replace an actuator that fails the low temperature torque test would not have the same issue shortly after installation (negating the benefit of performing the test). Mesaba Airlines concludes that the flight operations requirements instituted under AD 2007-17-07 provide an acceptable margin of safety until the modified actuator becomes available for retrofit.

   We disagree with the request to remove the requirement specified in paragraph (g)(3) of this AD. Bombardier and TCCA are discussing possible terminating action for Part C (low temperature torque test) of Bombardier Service Bulletin 601R-27-150. Although it has been proposed that the replacement of the current actuators with actuators incorporating the new inboard seal should be terminating action for the actuator cold soak requirement specified in Part C of the service bulletin, this has not yet been agreed to. Additionally, the new seal is still undergoing endurance testing at Eaton and is not yet approved.

   Once this new seal is developed, approved, and available, we might consider additional rulemaking. The actions specified in paragraph (g)(3) of this AD are intended to mitigate the potential of flap failures utilizing the solutions that are currently available. We have not revised this AD in this regard. However, according to the provisions of paragraph (h)(1) of the AD, operators may request an alternative method of compliance if the request includes data that prove that the new action would provide an acceptable level of safety.

   In regard to Mesaba Airlines' statement that there is no guarantee that a replacement actuator installed to replace an actuator failing the low temperature torque test would not have the same issue shortly after installation, we acknowledge that there is no guarantee that a replacement unit will not fail. However, replacing a known contaminated unit with a new unit, as required by paragraph (g)(3) of this AD, adequately addresses the identified unsafe condition. The actions in paragraph (g)(3) mitigate the risk of a failure as time in service increases.

   As stated earlier, we have revised paragraph (g)(3) of this AD to clarify that the actions apply only to certain actuators with more than 2,000 flight hours since new or actuators that have accumulated more than 2,000 flight hours since the pinion shaft seals were replaced. Bombardier has determined that the effects of oil contamination typically do not manifest until the actuators have accumulated over 6,000 flight hours, depending on aircraft utilization. The 24-month compliance time specified in paragraph (g)(3) of this AD is necessary to ensure that actuators that are in the range of 6,000 flight hours are inspected. We have not revised this AD in this regard.

Request To Allow Another Method of Compliance With Part C of the Service Bulletin

   Comair also requests that we allow the replacement of the inboard pinion shaft seals, P/Ns 853SC177-1/-2, as a method of compliance with Part C of the service bulletin. Comair notes that it has had and will have many actuators removed in accordance with Maintenance Requirement Manual, Certification Maintenance Requirements (CMR) Task C27-50-111-10, Functional Check of the Inboard Flap Actuator Torque Limiter. Comair states that actuators removed to comply with this CMR task should not also be subject to Part C of the service bulletin because the CMR task is an example of an event when the pinion seals must be replaced.

   We agree with the commenter that replacement actuators with inboard pinion shaft seals, P/Ns 853SC177-1/-2, are not subject to the actions in Part C of the service bulletin. As specified in paragraph 1.D., "Compliance," of the service bulletin, Part C only applies to certain actuators with more than 2,000 flight hours since new or since repair where it can be shown that the inboard pinion shaft seals P/Ns 853SC177-1/-2 were replaced. As stated previously, we have revised paragraph (g)(3) of this AD to clarify the actuators subject to the actions in that paragraph. If a repair was done and the inboard pinion shaft seals were replaced, the actuator would not be subject to Part C of the service bulletin unless the part had over 2,000 flight hours since the seal replacement.

Request To Allow Previous Alternative Methods of Compliance (AMOCs)

   Comair also requests that we add to the AMOC paragraph of this AD a statement that AMOCs approved previously according to AD 2007-17-07 are approved as AMOCs for the corresponding provisions of this AD.

   We agree that AMOCs approved previously in accordance with AD 2007-17-07 are acceptable for compliance with the corresponding provisions of this AD. We have revised paragraph (h)(1) of this AD accordingly.

Request To Remove Requirements

   Larry Nelson, a private citizen, states that the training requirements in AD 2007-17-07 and paragraphs (f)(3) and (g)(1) of the NPRM do not meet the requirements of sections 39.3 and 39.5 of the Federal Aviation Regulations (14 CFR 39.3 and 14 CFR 39.5). The commenter notes that section 14 CFR 39.3 states that rules "* * * apply to the following products: Aircraft, aircraft engines, propellers, and appliances." The commenter concludes that the training specified in the NPRM has nothing to do with the aircraft.

   The commenter adds that paragraphs (a) and (b) of section 14 CFR 39.5 state, "An unsafe condition exists in the product;" and "the condition is likely to exist or develop in other products of the same type design." The commenter states that the perceived unsafe condition, although part of the aircraft, actually applies to the specific parts mentioned in paragraphs (f)(1), (g)(2), and (g)(3) of the NPRM (flap flex shafts and flap actuators).

   We infer that the commenter requests we remove the requirements for training and for doing any actions related to parts (and not the airplane itself) from the NPRM. We disagree. Section 14 CFR 39.11 describes the types of actions that ADs can require, including "conditions and limitations you must comply with." In section 14 CFR 39.11, we intended to retain broad authority to require whatever types of corrective actions are determined to be most effective in addressing identified unsafe conditions.

   In this AD, we have found that one of the factors contributing to the identified unsafe condition is lack of training in operating an airplane when flap failure occurs in-flight (such as in freezing conditions). Due to the unsafe condition, we determined that these training requirements, in conjunction with the other requirements of this AD, are necessary to safely operate the airplane; and you must comply with them if you are an operator.

   As for the commenter's statement that the unsafe condition only applies to the part and not the airplane itself, we do not agree. We routinely issue ADs against the product that has a part installed that we have found to be unsafe. The AD applies to the product, and not the parts themselves, because parts that are not installed on operated products do not create an unsafe condition. As stated above, we determined that inadequate training and operating limitations also contributed to the unsafe condition of this AD. We have not revised the AD in this regard.

Request for Clarification of Compliance

   Larry Nelson also requests clarification on how to provide compliance documentation for the operations/dispatch and flight crewmembers' training specified in paragraph (f)(3) of this AD. The commenter states that section 39.11 of the Federal Aviation Regulations (14 CFR 39.11) specifies, "Airworthiness directives specify inspections you must carry out, conditions and limitations you must comply with, and any actions you must take to resolve an unsafe condition." The commenter states that this requirement would be met until one or more parts are changed. The commenter notes that since this NPRM is written against the airplane and does not include the specific parts addressed in the AD, NPRM, and service bulletin, it would therefore be difficult to manage.

   We find that clarification is necessary. As stated in paragraph (f)(3) of this AD, the training on the information in paragraph (f)(2) of this AD must be approved by the Principal Operations Inspector (POI). The method for documenting compliance should be included in the training approved by the POI. However, the method in which operators implement training in their operations and the method in which operators document compliance may vary greatly. Therefore, we have not included that information in this AD. We have not revised this AD in this regard.

Conclusion

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