AD 2000-10-12

This amendment adopts a new airworthiness directive (AD), applicable to certain Boeing Model 747-400 series airplanes. This action requires repetitive inspections to detect damage or deflection of the crew rest heat exchanger, and follow-on actions, if necessary. This amendment is prompted by reports of cracking and buckling of the front edge of the crew rest heat exchanger on several airplanes. The actions specified in this AD are intended to detect and correct damage or deflection of the crew rest heat exchanger, which could result in jamming of the rudder or elevator control cables, and consequent reduced controllability of the airplane.

Final rule; request for comments.

2000-10-12 BOEING: Amendment 39-11736. Docket 2000-NM-75-AD. \n\n\tApplicability: Model 747-400 series airplanes, line numbers 1 through 1205 inclusive, certificated in any category, and equipped with dual crown skin heat exchangers. \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 (c) 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 detect and correct damage or deflection of the crew rest heat exchanger, which could result in jamming of the rudder or elevator control cables, and consequent reduced controllability of the airplane, accomplish the following: \n\nRepetitive Inspections \n\t(a)\tWithin 1,200 flight hours or 90 days after the effective date of this AD, whichever occurs first, perform a general visual inspection of the crew rest heat exchanger to detect deflection or damage, in accordance with Boeing Alert Service Bulletin 747-21A2412, dated January 20, 2000. Repeat the inspection thereafter at intervals not to exceed 2,500 flight hours. \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, and may 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\nCorrective Action \n\t(b)\tIf any damage or deflection is detected during any inspection required by paragraph (a) of this AD, prior to further flight, replace the discrepant heat exchanger with a new heat exchanger, and measure the thickness of the material of the discrepant heat exchanger, in accordance with Boeing Alert Service Bulletin 747-21A2412, dated January 20, 2000. If the material is greater than or equal to 0.028 inches thick but less than or equal to 0.038 inches thick (>0.028 but >0.038 inches thick), send the damaged heat exchanger and inspection results to the Manager of Service Bulletin Engineering, Boeing Commercial Airplane Group, P.O. Box 3707, Seattle, Washington 98124. \n\n\tNOTE 3: There is a typographical error in the Accomplishment Instructions on page 10 of thealert service bulletin. Item G. under the heading "Inspection and Replacement of the Heat Exchanger (All Airplanes)" reads, "If the material thickness is between 0.028 - 0.034 inches(,) send the damaged heat exchanger and your inspection results to Boeing." The number "0.034" should read "0.038." \n\nAlternative Methods of Compliance \n\n\t(c)\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 Aircraft Certification Office (ACO), 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, Seattle ACO. \n\n\tNOTE 4: 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(d)\tSpecial flight permits may be issued in accordance withsections 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(e)\tThe actions shall be done in accordance with Boeing Alert Service Bulletin 747-21A2412, dated January 20, 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 Boeing 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\nEffective Date \n\n\t(f)\tThis amendment becomes effective on June 8, 2000.

The FAA has received reports indicating that cracking and buckling of the forward edge of the crew rest heat exchanger has been found on several airplanes. Investigation revealed that certain heat exchangers were manufactured with material that is too thin. On one airplane, the heat exchanger buckled and bulged enough to make contact with the rudder and elevator cables located below the heat exchanger. Such contact between the heat exchanger and the rudder and elevator control cables could eventually dislodge pieces of the heat exchanger or adjacent fasteners. Dislodged pieces or fasteners could cause a jam of the rudder or elevator control cables. This condition, if not corrected, could result in reduced controllability of the airplane. \n\nExplanation of Relevant Service Information \n\n\tThe FAA has reviewed and approved Boeing Alert Service Bulletin 747-21A2412, dated January 20, 2000. The alert service bulletin describes procedures for repetitivegeneral visual inspections to detect damage or deflection of the crew rest heat exchanger, and follow-on actions, if necessary. If damage or deflection is found, follow-on actions include replacement of the affected heat exchanger with a new heat exchanger, and measurement of the thickness of material of the discrepant heat exchanger. If the thickness of the material is within certain limits, the alert service bulletin specifies that the discrepant heat exchanger should be returned to Boeing. \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 detect and correct cracking or buckling of the crew rest heat exchanger, which could result jamming of the rudder or elevator control cables, and consequent reduced controllability of the airplane. This AD requires accomplishment of the actions specified in the alert service bulletin described previously, except as discussed below. \n\nDifference Between This AD and the Alert Service Bulletin \n\n\tOperators should note that there is a typographical error in the Accomplishment Instructions on page 10 of the alert service bulletin. Item G. under the heading "Inspection and Replacement of the Heat Exchanger (All Airplanes)" reads, "If the material thickness is between 0.028 - 0.034 inches(,) send the damaged heat exchanger and your inspection results to Boeing." The number "0.034" should read "0.038." "NOTE 3" has been included in this AD for clarification of this point. \n\nInterim Action \n\n\tThis is considered to be interim action until final action is identified, at which time the FAA may consider further rulemaking. \n\nCost Impact \n\n\tNone of the airplanes affected by this action are on the 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 affectedby 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. Register 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 1 work hour to accomplish the required inspection, at an average labor rate of $60 per work hour. Based on these figures, the cost impact of this AD would be $60 per airplane, per inspection cycle. \n\nDetermination 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 afterthe 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 2000-NM-75-AD." The postcard will be date stamped and returned to the commenter. \n\nRegulatory Impact \n\n\tThe 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. \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. \n\nAdoption of the Amendment \n\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\nPART 39 - AIRWORTHINESS DIRECTIVES \n\t1. The authority citation for part 39 continues to read as follows: \nAuthority: 49 U.S.C. 106(g), 40113, 44701. \n§ 39.13 (Amended) \n\t2. Section 39.13 is amended by adding the following new airworthiness directive: