[Federal Register Volume 60, Number 89 (Tuesday, May 9, 1995)] [Proposed Rules] [Pages 24589-24592] From the Federal Register Online via the Government Publishing Office [www.gpo.gov] [FR Doc No: 95-11356] ----------------------------------------------------------------------- DEPARTMENT OF TRANSPORTATION 14 CFR Part 39 [Docket No. 94-NM-107-AD] Airworthiness Directives; British Aerospace Model ATP Airplanes AGENCY: Federal Aviation Administration, DOT. ACTION: Supplemental notice of proposed rulemaking; reopening of comment period. ----------------------------------------------------------------------- [[Page 24590]] SUMMARY: This document revises an earlier proposed airworthiness directive (AD), which would have superseded an existing AD that is applicable to all British Aerospace Model ATP airplanes. The existing AD currently requires inspections to detect cracking of the aft end of the wing rib boom angles on the left and right engine, and repair or replacement of the wing rib boom angle assemblies, if necessary. The existing AD was prompted by the detection of cracks in the engine outboard rib boom angles at the main landing gear (MLG) actuator attachment point. Its required actions are intended to prevent structural failure of the actuator attachment point, which could lead to collapse of the MLG. The previously proposed action would have limited the applicability of the rule to certain airplanes; revised the initial inspection threshold for certain modified airplanes; and would have required that modified boom angles be installed whenever replacement is necessary. This action revises the proposed rule by correcting the actions necessary to be accomplished for one specific type of cracking condition. DATES: Comments must be received by June 1, 1995. ADDRESSES: Submit comments in triplicate to the Federal Aviation Administration (FAA), Transport Airplane Directorate, ANM-103, Attention: Rules Docket No. 94-NM-107-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 Jetstream Aircraft, Inc., P.O. Box 16029, Dulles International Airport, Washington, DC 20041-6029. This information may be examined at the FAA, Transport Airplane Directorate, 1601 Lind Avenue, SW., Renton, Washington. FOR FURTHER INFORMATION CONTACT: William Schroeder, Aerospace Engineer, Standardization Branch, ANM-113, FAA, Transport Airplane Directorate, 1601 Lind Avenue, SW., Renton, Washington 98055-4056; telephone (206) 227-2148. 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 94-NM-107-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-103, Attention: Rules Docket No. 94-NM-107-AD, 1601 Lind Avenue, SW., Renton, Washington 98055-4056. Discussion A proposal to amend part 39 of the Federal Aviation Regulations (14 CFR part 39) to add an airworthiness directive (AD), applicable to certain British Aerospace Model ATP airplanes, was published as a notice of proposed rulemaking (NPRM) in the Federal Register on January 18, 1995 (60 FR 3581). That NPRM would have superseded an existing airworthiness directive (AD) that is applicable to all British Aerospace Model ATP series airplanes. The existing AD currently requires inspections to detect cracking of the aft end of the wing rib boom angles on the left and right engine, and repair or replacement of the wing rib boom angle assemblies, if necessary. The existing AD was prompted by the detection of cracks in the engine outboard rib boom angles at the main landing gear (MLG) actuator attachment point. The NPRM proposed to limit the applicability of the existing rule to only a certain number of airplanes; revise the initial inspection threshold, depending on whether or not certain modifications have been accomplished on the boom angles; and require that modified boom angles be installed whenever replacement is necessary. Since the issuance of that NPRM, the FAA has recognized that one of the corrective actions proposed for certain cracking indications was incorrectly stated. Specifically, proposed paragraph (f) describes the actions that are to be taken if visual inspections reveal that one rib boom angle is cracked, and the crack extends beyond bolt hole Y or into bolt hole A. For conditions of this type of cracking, the NPRM proposed to require that operators repeat the inspections of the rib boom angle for additional crack propagation at intervals of 50 hours time-in-service. If no additional cracking was detected during any of the repetitive inspections, operators would be required to repair the rib boom angle or replace the rib boom angle assembly within one month. However, if additional cracking was detected, operators would be required to repair or replace prior to further flight. Those proposed corrective actions were inadvertently iterated in the NPRM. They are incorrect and, as stated, are unacceptable as corrective action to address the described cracking conditions. Additionally, they are at variance with the corrective action recommended by the manufacturer and described in the service bulletin referenced in the NPRM as the appropriate source of service information (i.e., British Aerospace Service Bulletin ATP-57-13, Revision 5, dated June 3, 1994). Instead, the action that must be taken to address initial findings of the described cracking is either the repair of the wing boom angle or replacement of the wing boom angle assembly, prior to further flight. The FAA has determined that the proposed rule must be revised to require this specific corrective action. Since this change expands the scope of the originally proposed rule, the FAA has determined that it is necessary to reopen the comment period to provide additional opportunity for public comment. The FAA estimates that 10 airplanes of U.S. registry would be affected by this proposed AD. The inspections that are currently required by AD 93-14-08 take approximately 2 work hours per airplane to accomplish. The average labor rate is $60 per work hour. Based on these figures, the total cost impact of the current inspection requirements AD on U.S. operators is estimated to be $1,200, or $120 per airplane, per inspection cycle. The total cost impact figure discussed above is based on assumptions that no operator has yet accomplished any of [[Page 24591]] the proposed requirements of this AD action, and that no operator would accomplish those actions in the future if this AD were not adopted. However, since AD 93-14-08 became effective on September 3, 1993, the FAA assumes that at least the initial inspection already has been performed on several of the affected airplanes. Thus, the total cost impact of this proposed AD may be reduced by the amount of the costs associated with those inspections that have already been accomplished. Additionally, since this proposed AD would extend the compliance time for the initial inspection of some airplanes, it has the effect of reducing the economic burden for operators of those airplanes, since it would preclude scheduling an airplane for inspections at a time earlier than is necessary. Should replacement of the boom angles with modified boom angles be necessary, it would require approximately 150 work hours to accomplish, at an average labor charge of $60 per work hour. Required parts would cost approximately $3,800 per airplane. 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 (44FR 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. App. 1354(a), 1421 and 1423; 49 U.S.C. 106(g); and 14 CFR 11.89. Sec. 39.13 [Amended] 2. Section 39.13 is amended by removing amendment 39-8632 (58 FR 42194, August 9, 1993), and by adding a new airworthiness directive (AD), to read as follows: British Aerospace: Docket 94-NM-107-AD. Supersedes AD 93-14-08, Amendment 39-8632. Applicability: Model ATP airplanes; serial numbers 2002 through 2063, 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 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 use the authority provided in paragraph (j) to request approval from the FAA. This approval may address either no action, if the current configuration eliminates the unsafe condition; or different actions necessary to address the unsafe condition described in this AD. Such a request should include an assessment of the effect of the changed configuration on the unsafe condition addressed by this AD. In no case does the presence of any modification, alteration, or repair remove any airplane from the applicability of this AD. Compliance: Required as indicated, unless accomplished previously. To prevent structural failure of the actuator attachment point, which could lead to collapse of the main landing gear (MLG), accomplish the following: (a) Conduct a detailed visual inspection to detect cracking of the aft end of the engine outboard rib boom angles under the wing rib outboard of the left and right engine, in accordance with British Aerospace Service Bulletin ATP-57-13, Revision1, dated January 15, 1993; or Revision 5, dated June 3, 1994; at the applicable time indicated below. (1) For airplanes on which Modification 10313A (reference British Aerospace Service Bulletin ATP-56-16-1013A, Revision 1, dated July 2, 1994) has not been accomplished: Conduct the initial inspection within 400 hours time-in-service after September 8, 1993 (the effective date of AD 93-14-08, amendment 39-8632), or within 12 months since airplane manufacture, whichever occurs later. (2) For airplanes on which Modification 10313A has been accomplished (modified inboard and outboard boom angles on both the left wing and right wing): Conduct the initial inspection prior to the accumulation of 30,000 landings on the boom angle assembly or within 12 months after the effective date of this AD, whichever occurs later. (b) For the purposes of compliance with this AD, the following apply: (1) Repair of cracked rib boom angles shall be accomplished in accordance with a method approved by the Manager, Standardization Branch, ANM-113, FAA, Transport Airplane Directorate. (2) Replacement of cracked rib boom angle assemblies with modified assemblies shall be accomplished in accordance with British Aerospace Service Bulletin ATP-57-16-10313A, Revision 1, dated July 2, 1994 (as corrected by Erratum 2, dated August 30, 1994). Prior to the accumulation of 30,000 landings on the replaced (modified) boom angle assembly, repeat the inspection in accordance with paragraph (a) of this AD. (c) If no crack is detected: Repeat the detailed visual inspection at intervals not to exceed 3,000 landings or 12 months, whichever occurs first. (d) If any crack is detected on only one rib boom angle, and that crack does not extend beyond bolt hole X: Repeat the detailed visual inspection of the rib boom angle for additional crack propagation at intervals not to exceed 300 hours time-in-service. (1) If no additional crack propagation is detected during any of the repetitive inspections: Within 6 months after discovery of the crack, either repair the rib boom angle or replace the rib boom angle assembly in accordance with paragraph (b) of this AD. (2) If any of the repetitive inspections reveal that crack propagation has reached or extends beyond bolt hole Y or into bolt hole A: Prior to further flight, either repair the rib boom angle or replace the rib boom assembly in accordance with paragraph (b) of this AD. (e) If any crack is detected on only one rib boom angle, and that crack extends beyond bolt hole X, but not beyond bolt hole Y or down towards bolt hole A: Repeat the detailed visual inspection of the rib boom angle for additional crack propagation at intervals not to exceed 100 hours time-in-service. (1) If no additional crack propagation is detected during any of the repetitive inspections: Within 3 months after discovery of the crack, either repair the rib boom angle or replace the rib boom angle assembly in accordance paragraph (b) of this AD. (2) If any of the repetitive inspections reveal that crack propagation has reached or extends beyond bolt hole Y or into bolt hole A: Prior to further flight, either repair the rib boom angle or replace the rib boom angle assembly in accordance with paragraph (b) of this AD. (f) If any crack is detected on only one rib boom angle, and that crack extends beyond bolt hole Y or into bolt hole A: Prior to further flight, either repair the rib boom angle or replace the rib boom angle assembly in accordance with paragraph (b) of this AD. (g) If any crack is detected on both rib boom angles, and cracks do not extend beyond bolt hole X: Repeat the detailed visual inspection of the rib boom angles for additional crack propagation at intervals not to exceed 100 hours time-in-service. [[Page 24592]] (1) If no additional crack propagation is detected during any of the repetitive inspections: Within 3 months after discovery of the cracks, either repair the rib boom angles or replace the rib boom angle assembly in accordance with paragraph (b) of this AD. (2) If any of the repetitive inspections reveal that crack propagation has reached or extends beyond bolt hole Y or into bolt hole A: Prior to further flight, either repair the rib boom angles or replace the rib boom angle assembly in accordance with paragraph (b) of this AD. (h) If any crack is detected on both rib boom angles, and cracks extend beyond bolt hole X, but not beyond bolt hole Y or down towards bolt hole A: Repeat the detailed visual inspection of the rib boom angles for additional crack propagation at intervals not to exceed 50 hours time-in-service. (1) If no additional crack propagation is detected during any of the repetitive inspections: Within 1 month after discovery of the cracks, either repair the rib boom angles or replace the rib boom angle assembly in accordance with paragraph (b) of this AD. (2) If any of the repetitive inspections reveal that crack propagation has reached or extends beyond bolt hole Y or into bolt hole A: Prior to further flight, either repair the rib boom angles or replace the rib boom angle assembly in accordance with paragraph (b) of this AD. (i) If any crack is detected on both rib boom angles, and cracks extend beyond bolt hole Y or into bolt hole A: Prior to further flight, either repair the rib boom angles or replace the rib boom angle assembly in accordance with paragraph (b) of this AD (j) 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, Standardization Branch, ANM-113, FAA, Transport Airplane Directorate. Operators shall submit their requests through an appropriate FAA Principal Maintenance Inspector, who may add comments and then send it to the Manager, Standardization Branch, ANM-113. Note 2: Information concerning the existence of approved alternative methods of compliance with this AD, if any, may be obtained from the Standardization Branch, ANM-113. Note 3: Alternative methods of compliance previously granted for amendment 39-8632, AD 93-14-08, continue to be considered as acceptable alternative methods of compliance with this amendment. (k) 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. Issued in Renton, Washington, on May 3, 1995. James V. Devany, Acting Manager, Transport Airplane Directorate, Aircraft Certification Service. [FR Doc. 95-11356 Filed 5-8-95; 8:45 am] BILLING CODE 4910-13-U