AD 99-22-09

This amendment adopts a new airworthiness directive (AD), applicable to certain Boeing Model 747-400 series airplanes. This action requires an inspection of the crew rest area heat exchangers to detect deflection or interference with the flight control cables; and various follow-on actions. This action also requires replacement of certain nutplate attachment rivets that attach the heat exchangers to the airframe with stronger rivets. This amendment is prompted by a report of interference between insulation blankets adjacent to the heat exchangers and flight control cables. The actions specified in this AD are intended to prevent a reduction in maximum rudder and elevator surface deflection due to the separation of heat exchangers from the body frame, which could result in reduced controllability of the airplane.

Final rule; request for comments

99-22-09 BOEING: Amendment 39-11387. Docket 99-NM-178-AD. \n\n\tApplicability: Model 747-400 series airplanes; as listed in Boeing Alert Service Bulletin 747-53A2430, dated June 10, 1999; certificated in any category. \n\n\tNOTE 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 (d) 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. \n\n\tCompliance: Required as indicated, unless accomplished previously. \n\n\tTo prevent a reduction in maximum rudder and elevator surface deflection due to the separation of heat exchangers from the body frame, which could result in reduced controllability of the airplane, accomplish the following: \n\nOne-Time Inspection \n\n\t(a)\tWithin 400 flight hours or 30 days after the effective date of the AD, whichever occurs earlier, perform a one-time general visual inspection of the crew rest area (CRA) heat exchangers to detect deflection or interference with the flight control cables, in accordance with Boeing Alert Service Bulletin 747-53A2430, dated June 10, 1999. \n\n\tNOTE 2: For the purposes of this AD, a general visual inspection is defined as: "A visual examination of an interior or exterior area, installation, or assembly to detect obvious damage, failure, or irregularity. This level of inspection is made under normally available lighting conditions such as daylight, hangar lighting, flashlight, or drop-light, andmay require removal or opening of access panels or doors. Stands, ladders, or platforms may be required to gain proximity to the area being checked." \n\nReplacement \n\n\t(b)\tIf no deflection or interference is detected, within 6,000 flight hours after accomplishment of the inspection required by paragraph (a) of this AD, measure the electrical conductivity of the nutplate attachment rivets that attach the heat exchangers to the airframe at station 1920 to determine the rivet material, in accordance with Boeing Alert Service Bulletin 747-53A2430, dated June 10, 1999. Prior to further flight, replace any rivets not made of 2017-T4 aluminum with rivets made of 2017-T4 aluminum, in accordance with the alert service bulletin. \n\n\t(c)\tIf any deflection or interference is detected during the inspection required by paragraph (a) of this AD, prior to further flight, accomplish paragraphs (c)(1) and (c)(2) of this AD. \n\n\t\t(1)\tPerform a one-time general visual inspection of the CRA heat exchanger panels, pitot-static tubes, and air distribution ducts in the area of station 1920 to detect damage, in accordance with Boeing Alert Service Bulletin 747-53A2430, dated June 10, 1999. If any damage is detected, prior to further flight, repair in accordance with a method approved by the Manager, Seattle Aircraft Certification Office (ACO), FAA, Transport Airplane Directorate. For a repair method to be approved by the Manager, Seattle ACO, as required by this paragraph, the Manager's approval letter must specifically reference this AD. \n\n\t\t(2)\tRemove the nutplates and attachment rivets that attach the heat exchangers to the airframe at station 1920, and replace with new nutplates and rivets made of 2017-T4 aluminum, in accordance with Boeing Alert Service Bulletin 747-53A2430, dated June 10, 1999 \n\nAlternative Methods of Compliance \n\n\t(d)\tAn 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, Seattle ACO. Operators shall submit their requests through an appropriate FAA Principal Maintenance Inspector, who may add comments and then send it to the Manager, Seattle ACO. \n\n\tNOTE 3: Information concerning the existence of approved alternative methods of compliance with this AD, if any, may be obtained from the Seattle ACO. \n\nSpecial Flight Permits \n\n\t(e)\tSpecial 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. \n\nIncorporation by Reference \n\n\t(f)\tExcept as provided by paragraph (c)(1) of this AD, the actions shall be done in accordance with Boeing Alert Service Bulletin 747-53A2430, dated June 10, 1999. 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 fromBoeing Commercial Airplane Group, P.O. Box 3707, Seattle, Washington 98124-2207. Copies may be inspected at the FAA, Transport Airplane Directorate, 1601 Lind Avenue, SW., Renton, Washington; or at the Office of the Federal Register, 800 North Capitol Street, NW., suite 700, Washington, DC. \n\n\t(g)\tThis amendment becomes effective on November 10, 1999.

The FAA has received a report indicating that the rudder and elevator of a Boeing Model 747-400 series airplane were "stiff." Further investigation revealed that the nutplate attachment rivets that attach the crew rest area (CRA) heat exchangers to the airframe at station 1920 had failed. When the CRA air supply fan was on, air pressure caused the heat exchangers to deflect downwards and push adjacent insulation blankets into the flight control cables, causing the stiffness of the flight controls. This condition, if not corrected, could result in reduced maximum deflection of the rudder and elevator surfaces, which could result in reduced controllability of the airplane. \n\n\tExamination of failed rivets revealed that the rivets were not made of 2017-T4 aluminum, which was the rivet material specified in the engineering drawings. Instead, the rivets were made of lower-strength 1100-F aluminum. The airplane manufacturer has determined that rivets madeof the proper material were installed during production on airplanes after line number 1205. \n\nExplanation of Relevant Service Information \n\n\tThe FAA has reviewed and approved Boeing Alert Service Bulletin 747-53A2430, dated June 10, 1999, which describes procedures for inspection of the CRA heat exchangers to detect deflection or interference with the flight control cables; and an inspection of the heat exchanger panels, pitot-static tubes, and air distribution ducts in that area to detect damage, if necessary. If any damage is detected, the alert service bulletin specifies to contact the manufacturer for repair instructions. The alert service bulletin also describes procedures for performing an electrical conductivity measurement of the nutplate attachment rivets that attach the heat exchangers to the airframe to determine the rivet material, and replacement of certain rivets with stronger rivets. Accomplishment of the actions specified in the alert service bulletin is intended to adequately address the identified unsafe condition. \n\nExplanation of Requirements of the Rule \n\n\tSince an unsafe condition has been identified that is likely to exist or develop on other airplanes of the same type design, this AD is being issued to prevent a reduction in maximum rudder and elevator surface deflection due to the separation of heat exchangers from the body frame, which could result in reduced controllability of the airplane. This AD requires accomplishment of the actions specified in the alert service bulletin described previously, except as described below. \n\nDifferences Between Rule and Alert Service Bulletin \n\n\tOperators should note that, although the alert service bulletin specifies that the manufacturer may be contacted for disposition of certain repair conditions, this AD requires the repair of those conditions to be accomplished in accordance with a method approved by the FAA. \n\nCost Impact \n\n\tNone of the airplanes affected by this action are onthe U.S. Register. All airplanes included in the applicability of this rule currently are operated by non-U.S. operators under foreign registry; therefore, they are not directly affected by this AD action. However, the FAA considers that this rule is necessary to ensure that the unsafe condition is addressed in the event that any of these subject airplanes are imported and placed on the U.S. \n\nRegister in the future. \n\n\tShould an affected airplane be imported and placed on the U.S. Register in the future, it would require approximately 2 work hours to accomplish the required inspection, at an average labor rate of $60 per work hour. Based on these figures, the cost impact of this inspection would be $120 per airplane. \n\n\tIt would require approximately 3 hours to accomplish the required replacement, at an average labor rate of $60 per work hour. Required parts would cost approximately $17 per airplane. Based on these figures, the cost impact of this replacement would be $197per airplane.\n\n Determination of Rule's Effective Date \n\n\tSince this AD action does not affect any airplane that is currently on the U.S. register, it has no adverse economic impact and imposes no additional burden on any person. Therefore, prior notice and public procedures hereon are unnecessary and the amendment may be made effective in less than 30 days after publication in the Federal Register. \n\nComments Invited \n\n\tAlthough this action is in the form of a final rule and was not preceded by notice and opportunity for public comment, comments are invited on this rule. Interested persons are invited to comment on this 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 under the caption "ADDRESSES." All communications received on or before the closing date for comments will be considered, and this rule may be amended in light of the comments received. Factual information that supports the commenter's ideas and suggestions is extremely helpful in evaluating the effectiveness of the AD action and determining whether additional rulemaking action would be needed. \n\n\tComments are specifically invited on the overall regulatory, economic, environmental, and energy aspects of the rule that might suggest a need to modify the 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 that summarizes each FAA-public contact concerned with the substance of this AD will be filed in the Rules Docket. \n\n\tCommenters wishing the FAA to acknowledge receipt of their comments submitted in response to this rule must submit a self-addressed, stamped postcard on which the following statement is made: "Comments to Docket Number 99-NM-178-AD." The postcard will be date stamped and returned to the commenter. \n\nRegulatory Impact \n\n\tThe regulations adopted herein will 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 final rule does not have sufficient federalism implications to warrant the preparation of a Federalism Assessment. \n\n\tFor 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." \n\nList of Subjects in 14 CFR Part 39 \n\n\tAir transportation, Aircraft, Aviation safety, Incorporation by reference, Safety. \nAdoption of the Amendment \n\tAccordingly, 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:\n\n PART 39 - AIRWORTHINESS DIRECTIVES \n\n\t1. The authority citation for part 39 continues to read as follows: Authority: 49 U.S.C. 106(g), 40113, 44701. § 39.13 (Amended) \n\t2. Section 39.13 is amended by adding the following new airworthiness directive: