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 all BAE Systems (Operations) Limited Model Avro 146-RJ series airplanes was published in the Federal Register on March 24, 2004 (69 FR 13760). That action proposed to require replacing the existing digital flight guidance computer(s) (DFGC) with a new flight computer(s).
Comments
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 Explanation of Unsafe Conditions and Results
Two commenters state that the unsafe condition and results specified in the AD are derived from an incorrect combination of two completely unrelated conditions. Both commenters state that the premature flare condition is due to erroneous radio altimeter data provided to the DFGCs being undetected. One of the commenters, the airplane manufacturer, states that inappropriate force that the pilot applied to the control stick resulted from the flightcrew's uncertainty as to whether the autopilot was engaged or not. The commenter requests that the Summary and Discussion sections of the proposed AD be rewritten to reflect that the two unsafe conditions are unrelated. The other commenter, the DFGC manufacturer, requests that the body of the proposed AD be rewritten to reflect that the two unsafe conditions are unrelated.
The FAA agrees that the premature flare condition and application of inappropriate force to the control stick are unrelated. Therefore, we have rewritten the statement of unsafe conditions in the Summary and body of the AD to reflect the commenters' statements. However, the Discussion section of the AD is not repeated in the final rule, so no change to the final rule is necessary in that regard.
Request To Revise Wording Describing the Action to Replace
Onecommenter, the DFGC manufacturer, requests that the wording of paragraph (a) of the proposed AD describing the replacement of the "existing * * * DFGC" with a "new DFGC(s) * * *" be revised to read "a modified DFGC." The commenter states that the unsafe conditions result from erroneous data from external sources being supplied to DFGCs that are in perfect working order. The commenter indicates that specifying replacement of an existing DFGC with a new DFGC implies that the DFGC was seriously flawed and required a major redesign. The commenter states that only minor software adjustments were necessary to enhance DFGC monitoring capabilities and no redesign was needed to address the unsafe conditions. Following the same reasoning, the commenter requests that the heading of paragraph (a) be changed from "Replacement" to "Modification."
We understand the commenter's position and agree that clarification is necessary. DFGCs returned to the manufacturer for upgrade, then returned to service certainly have been modified. However, we do not agree that the word "new" carries such negative impact, since any new DFGC produced by the manufacturer will also contain the upgrade. Therefore, the wording of the summary of the section and paragraph (a) of this AD has been changed to read "with a new or modified DFGC(s)."
We do not agree that the heading of paragraph (a) should be changed from "Replacement" to "Modification." Though the DFGC is being switched for an upgraded DFGC, and will itself be upgraded by the manufacturer for return to service, the DFGC is still being replaced with another DFGC, not modified by the operator. No change to the final rule is necessary in this regard.
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 changes described previously. The FAA has determined that these changes will neither increase the economic burden on any operator nor increase the scope of the AD.
Cost Impact
The FAA estimates that 36 airplanes of U.S. registry will be affected by this AD, that it will take approximately 1 work hour per airplane to accomplish the required actions, and that the average labor rate is $65 per work hour. Required parts will cost approximately $4,250 per DFGC (some airplanes may have 2 DGFCs). Based on these figures, the cost impact of the AD on U.S. operators is estimated to be between $4,315 and $8,565 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: