AD 2006-21-05

This amendment adopts a new airworthiness directive (AD), applicable to certain Boeing Model 747-400, 777-200, and 777-300 series airplanes. This AD requires, for certain airplanes, replacing the cell stack of the flight deck humidifier with a supplier-tested cell stack, or replacing the cell stack with a blanking plate and subsequently deactivating the flight deck humidifier. For certain other airplanes, this AD requires an inspection of the flight deck humidifier to determine certain part numbers and replacing the cell stack if necessary. This AD also allows blanking plates to be replaced with cell stacks. The actions specified by this AD are intended to prevent an increased pressure drop across the humidifier and consequent reduced airflow to the flight deck, which could result in the inability to clear any smoke that might appear in the flight deck. This action is intended to address the identified unsafe condition.

Final rule.

2006-21-05 Boeing: Amendment 39-14789. Docket 2000-NM-360-AD. \n\n\n\tApplicability: Model 747-400, 777-200, and 777-300 series airplanes, certificated in any category; as identified in Boeing Service Bulletin 747-21A2414, Revision 3, dated May 12, 2006; and Boeing Service Bulletin 777-21A0048, Revision 3, dated May 12, 2006. \n\tCompliance: Required as indicated, unless accomplished previously. \n\tTo prevent an increased pressure drop across the humidifier and consequent reduced airflow to the flight deck, which could result in the inability to clear any smoke that might appear in the flight deck, accomplish the following: \n\nCell Stack Replacement: Model 747-400 Series Airplanes \n\n\t(a) For Model 747-400 series airplanes identified as Group 1 in Boeing Service Bulletin 747-21A2414, Revision 3, dated May 12, 2006: Within 90 days after the effective date of this AD, do the replacement specified in paragraph (a)(1) or (a)(2) of this AD. For flight deck humidifiers with a blanking plate:If the blanking plate is removed and a new or supplier-tested cell stack is installed, the replacement must be done in accordance with the Accomplishment Instructions of Hamilton Sundstrand Service Bulletins 821486-21-01, dated March 15, 2000; and after the replacement, the flight deck humidifier may be activated in accordance with the Accomplishment Instructions of Boeing Service Bulletin 747-21-2405, Revision 4, dated July 29, 1999. \n\n\tNote 1: Boeing Service Bulletin 747-21A2414, Revision 3, dated May 12, 2006, specifies Group 1 as "all 747-400 airplanes with Hamilton Sundstrand flight deck humidifier 821486-01." The correct part number (P/N) for the humidifier is 821486-1. \n\n\t(1) Replace the cell stack of the flight deck humidifier with a supplier-tested cell stack, in accordance with Part 1 of the Accomplishment Instructions of Boeing Service Bulletin 747-21A2414, Revision 3, dated May 12, 2006. \n\t(2) Replace the cell stack of the flight deck humidifier with a blanking plateand, before further flight, deactivate the flight deck humidifier, in accordance with Part 2 of the Accomplishment Instructions of Boeing Service Bulletin 747-21A2414, Revision 3, dated May 12, 2006. \n\n\tNote 2: Boeing Service Bulletin 747-21A2414, Revision 3, dated May 12, 2006, refers to Boeing Service Bulletin 747-21-2405, Revision 4, dated July 29, 1999, as an additional source of service information for deactivating the humidifier. \n\n\tNote 3: Boeing Service Bulletin 747-21A2414, Revision 3, dated May 12, 2006, refers to Hamilton Sundstrand Service Bulletin 821486- 21-01, dated March 15, 2000, as an additional source of service information for the cell stack replacements. \n\n\t(b) Replacement of the cell stack before the effective date of this AD in accordance with Boeing Alert Service Bulletin 747- 21A2414, dated April 13, 2000; Revision 1, dated October 26, 2000; or Revision 2, dated July 7, 2005; is acceptable for compliance with the applicable requirements of paragraphs (a)(1) and (a)(2) of this AD. \n\nInspections/Records Review: Model 747-400 Series Airplanes \n\n\t(c) For Model 747-400 series airplanes identified as Groups 2 and 3 in Boeing Service Bulletin 747-21A2414, Revision 3, dated May 12, 2006: Within 90 days after the effective date of this AD, inspect the flight deck humidifier to determine whether P/N 821486-1 is installed, in accordance with Part 3 of the Accomplishment Instructions of Boeing Service Bulletin 747-21A2414, Revision 3, dated May 12, 2006. Instead of inspecting the flight deck humidifier, a \nreview of airplane maintenance records along with any other applicable data is acceptable if the P/N of the flight deck humidifier can be positively determined from that review or if it can be positively determined that the flight deck humidifier is not installed on the airplane. \n\t(1) If a P/N other than P/N 821486-1 is installed or if the flight deck humidifier is not installed, no further action is required by this paragraph. \n\t(2) IfP/N 821486-1 is installed, inspect the flight deck humidifier cell stack to determine whether P/N 821482-1 is installed and "DEV 13433" is not marked next to the cell stack P/N, in accordance with Part 3 of the Accomplishment Instructions of the service bulletin. Instead of inspecting the flight deck humidifier cell stack, a review of airplane maintenance records is acceptable if the P/N, including whether "DEV 13433" is marked next to the P/ N, of the flight deck humidifier cell stack can be positively determined from that review. \n\t(i) If the cell stack has P/N 821482-2 or 1003111-2, or if "DEV 13433" is marked next to P/N 821482-1, no further action is required by this paragraph. \n\t(ii) If the cell stack has P/N 821482-1 and does not have "DEV 13433" marked next to the cell stack P/N: Before further flight, do the replacement specified in paragraph (a) of this AD. \n\nCell Stack Replacement: Model 777-200 and -300 Series Airplanes \n\n\t(d) For Model 777-200 and 777-300 series airplanes identified as Groups 1 through 5 in Boeing Service Bulletin 777-21A0048, Revision 3, dated May 12, 2006: Within 90 days after the effective date of this AD, do the replacement specified in paragraph (d)(1) or (d)(2) of this AD. For flight deck humidifiers with a blanking plate: If a blanking plate is removed and a new or supplier-tested cell stack installed, the cell stack installation must be done in accordance with Part 3 of the Accomplishment Instructions of Boeing Service Bulletin 777-21A0048, Revision 3, dated May 12, 2006; and after the installation, the humidifier system may be activated in accordance with Accomplishment Instructions of Boeing Service Bulletin 777-21- 0035, Revision 1, dated October 19, 2000. \n\t(1) Replace the cell stack with a blanking plate, in accordance with Part 1 of the Accomplishment Instructions of Boeing Service Bulletin 777-21A0048, Revision 3, dated May 12, 2006; and, before further flight, deactivate the humidifier system in accordance with amethod approved by the Manager, Seattle Aircraft Certification Office (ACO), FAA, or in accordance with data meeting the certification basis of the airplane approved by an Authorized Representative for the Boeing Commercial Airplanes Delegation Option Authorization who has been authorized by the Manager, Seattle ACO, to make those findings. For a deactivation method to be approved, the deactivation must meet the certification basis of the airplane, and the approval must specifically reference this AD. \n\t(2) Replace the cell stack with a supplier-tested cell stack, in accordance with Part 2 of the Accomplishment Instructions of Boeing Service Bulletin 777-21A0048, Revision 3, dated May 12, 2006. \n\n\tNote 4: Boeing Service Bulletin 777-21A0048, Revision 3, dated May 12, 2006, refers to Hamilton Sundstrand Service Bulletin 816086- 21-01, dated March 15, 2000, as an additional source of service information for the cell stack replacement. \n\n\t(e) Replacement of the cell stack before theeffective date of this AD in accordance with Boeing Service Bulletin 777-21A0048, Revision 1, dated September 7, 2000; or Boeing Alert Service Bulletin 777-21A0048, Revision 2, dated July 14, 2005; is acceptable for compliance with the applicable requirements of paragraphs (d)(1) and (d)(2) of this AD. \n\nInspections/Records Review: Model 777-200 and -300 Series Airplanes \n\n\t(f) For Model 777-200 and 777-300 series airplanes identified as Groups 6 and 7 in Boeing Service Bulletin 777-21A0048, Revision 3, dated May 12, 2006: Within 90 days after the effective date of this AD, inspect the flight deck humidifier to determine if it is P/N 816086-1, in accordance with Part 4 of the Accomplishment Instructions of Boeing Service Bulletin 777-21A0048, Revision 3, dated May 12, 2006. Instead of inspecting the flight deck humidifier, a review of airplane maintenance records along with any other applicable data is acceptable if the P/N of the flight deck humidifier can be positively determinedfrom that review or if it can be positively determined that the flight deck humidifier is not installed on the airplane. \n\t(1) If a P/N other than P/N 816086-1 is installed or if the flight deck humidifier is not installed, no further action is required by this paragraph. \n\t(2) If P/N 816086-1 is installed, inspect the flight deck humidifier cell stack to determine whether P/N 822976-2 is installed and "DEV 13433" is not marked next to the cell stack P/N, in accordance with Part 4 of the Accomplishment Instructions of the service bulletin. Instead of inspecting the flight deck humidifier cell stack, a review of airplane maintenance records is acceptable if the P/N, including whether "DEV 13433" is marked next to the P/ N, of the flight deck humidifier cell stack can be positively determined from that review. \n\t(i) If the cell stack has P/N 822976-3 or 1003111-1, or if "DEV 13433" is marked next to P/N 822976-2, no further action is required by this paragraph. \n\t(ii) If the cell stack has P/N 822976-2 and does not have "DEV 13433" marked next to the cell stack P/N, before further flight, do the replacement specified in paragraph (d) of this AD. Doing the replacement of the cell stack with a blanking plate, in accordance with paragraph 3.A. of the Accomplishment Instructions of Hamilton Sundstrand Service Bulletin 816086-21-01, dated March 15, 2000; and the deactivation of the humidifier system, in accordance with the Accomplishment Instructions of Boeing Service Bulletin 777-21-0087, dated June 17, 2004; is acceptable for compliance with paragraph (d)(1) of this AD for those Group 7 airplanes listed in Boeing Service Bulletin 777-21-0087, dated June 17, 2004. \n\nActions Accomplished According to Previous Issue of Service Bulletin \n\n\t(g) Inspections accomplished before the effective date of this AD in accordance with Boeing Alert Service Bulletin 747-21A2414, Revision 2, dated July 7, 2005, are considered acceptable for compliance with the corresponding actionspecified in paragraph (c) of this AD. \n\t(h) Inspections accomplished before the effective date of this AD in accordance with Boeing Alert Service Bulletin 777-21A0048, Revision 2, dated July 14, 2005, are considered acceptable for compliance with the corresponding action specified in paragraph (f) of this AD. \n\nParts Installation \n\n\t(i) On Model 747-400 series airplanes: As of the effective date of this AD, no person may install a flight deck humidifier cell stack having P/N 821482-1, unless "DEV 13433" is also marked next to the cell stack P/N. \n\t(j) On Model 777-200 and 777-300 series airplanes: As of the effective date of this AD, no person may install a flight deck humidifier cell stack having P/N 822976-2, unless "DEV 13433" is also marked next to the cell stack P/N. \n\nAlternative Methods of Compliance \n\n\t(k)(1) In accordance with 14 CFR 39.19, the Manager, Seattle ACO, is authorized to approve alternative methods of compliance for this AD. \n\t(2) Before using any AMOCapproved in accordance with 14 CFR 39.19 on any airplane to which the AMOC applies, notify the appropriate principal inspector in the FAA Flight Standards Certificate Holding District Office. \n\nIncorporation by Reference \n\n\t(l) Unless otherwise specified in this AD, the actions must be done in accordance with the applicable service bulletins listed in Table 1 of this AD. 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. To get copies of this service information, contact Boeing Commercial Airplanes, P.O. Box 3707, Seattle, Washington 98124-2207. To inspect copies of this service information, go to the FAA, Transport Airplane Directorate, 1601 Lind Avenue, SW., Renton, Washington. For information on the availability of this material at the NARA, call (202) 741-6030, or go to http://www.archives.gov/federal_register/code_of_federal_regulations/ibr_locations.html. \n\n\n\n\n\nTABLE 1. MATERIAL INCORPORATED BY REFERENCE\nService Bulletin\nRevision level\nDate\nBoeing Service Bulletin 747-21A2414\n3\nMay 12, 2006\nBoeing Service Bulletin 747-21-2405\n4\nJuly 29, 1999\nBoeing Service Bulletin 777-21A0048\n3\nMay 12, 2006\nBoeing Service Bulletin 777-21-0035\n1\nOctober 19, 2000\nBoeing Service Bulletin 777-21-0087\nOriginal\nJune 17, 2004\nHamilton Sundstrand Service Bulletin 816086-21-01\nOriginal\nMarch 15, 2000\nHamilton Sundstrand Service Bulletin 821486-21-01\nOriginal\nMarch 15, 2000\n\nEffective Date \n\n\t(m) This amendment becomes effective on November 22, 2006.

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 certain Boeing Model 747-400, 777- 200, and 777-300 series airplanes was published as a second supplemental notice of proposed rulemaking (NPRM) in the Federal Register on January 4, 2006 (71 FR 299). That action proposed to require, for certain airplanes, replacing the cell stack of the flight deck humidifier with a supplier-tested cell stack, or replacing the cell stack with a blanking plate and subsequently deactivating the flight deck humidifier. For certain other airplanes, that action proposed to require an inspection of the flight deck humidifier to determine certain part numbers and replacing the cell stack if necessary. That action also proposed to allow blanking plates to be replaced with cell stacks. That action also proposed to add airplanes to the applicability. \n\nActions Since Second Supplemental NPRM (SNPRM) Was Issued \n\n\tSince we issued the second SNPRM, Boeing has issued Service Bulletin 747-21A2414, Revision 3, dated May 12, 2006; and Service Bulletin 777-21A0048, Revision 3, dated May 12, 2006. Boeing Alert Service Bulletin 747-21A2414, Revision 2, dated July 7, 2005; and Boeing Alert Service Bulletin 777-21A0048, Revision 2, dated July 14, 2005, were referenced as the appropriate sources of service information for doing certain actions proposed in the second SNPRM. Both service bulletins, Revision 3, contain essentially the same procedures as the corresponding service bulletins, Revision 2. We have revised this final rule to refer to Revision 3 of these service bulletins. \n\tWe have also added Boeing Alert Service Bulletin 747-21A2414, Revision 2, to paragraphs (b) and (g) of this final rule and added Boeing Alert Service Bulletin 777-21A0048, Revision 2, to paragraphs (e) and (h) of this final rule to allow credit for actions done in accordance with Revision 2 of the service bulletins. \n\tOperators should note that Boeing Service Bulletin 747-21A2414, Revision 3, dated May 12, 2006, specifies Group 1 as "all 747-400 airplanes with Hamilton Sundstrand flight deck humidifier 821486-01." However, the correct part number for the humidifier is 821486-1. We have added Note 1 to this final rule to indicate that Group 1 is identified as all 747-400 airplanes with Hamilton Sundstrand flight deck humidifier 821486-1. \n\nComments \n\n\tInterested persons have been afforded an opportunity to participate in the making of this amendment. Due consideration has been given to the comments received. \n\nSupport for the Second SNPRM \n\n\tBoeing, the manufacturer, concurs with the content of the second SNPRM. \n\nRequest To Remove Airplanes From the Second SNPRM \n\n\tUnited Airlines (UAL) does not agree with the contents of the second SNPRM for the Model 747-400 series airplanes and feels that regulatory action is not necessary to ensure the intent of the second SNPRM forthese airplanes. UAL states that it took immediate steps to comply with Boeing and Hamilton Sundstrand service bulletins specified in the second SNPRM. UAL notes that because the reliability of the humidifier was extremely poor at the time that the cell stack concern was identified, the humidifier cell stacks have been replaced many times since the year 2000. UAL states that the removed cell stacks were sent to Hamilton Sundstrand for repair and modification and that Hamilton Sundstrand is the sole source for repair and modification. Therefore, UAL concludes that the intent of the second SNPRM for the 747-400 airplanes can be satisfied by examining Hamilton Sundstrand's maintenance records for the cell stack. \n\tWe disagree. Regulatory action is necessary to ensure that Model 747-400 series airplanes do the actions in this final rule. A review by the airplane manufacturer of the Hamilton Sundstrand records shows that about 10 defective humidifier cell stacks are in circulation among the Model 747-400 fleet. This final rule will prevent any of those humidifiers, having cell stack part number (P/N) 821482-1, from being installed as replacements on any airplanes unless "DEV 13433" is marked next to the cell stack P/N. We have not changed the final rule in this regard. \n\tUAL also does not agree with the contents of the second SNPRM for the Model 777-200 series airplanes and feels that regulatory action is not necessary to ensure the intent of the second SNPRM for these airplanes. UAL states that the airplanes identified as Group 6 in Boeing Service Bulletin 777-21A0048, Revision 3, dated May 12, 2006, were added to the service bulletin because the airplanes were scheduled to have the humidifiers retrofitted as part of the crew rest project; however, the installation was canceled and no airplanes were retrofitted with the humidifiers. \n\tWe disagree. Regulatory action is necessary to ensure that Model 777-200 series airplanes do the actions in this final rule. A reviewby the airplane manufacturer of the Hamilton Sundstrand records shows that about 14 defective humidifier cell stacks are in circulation among the Model 777 fleet. This final rule will prevent any of those humidifiers, having cell stack P/N 822976-2, from being installed as replacements on any airplanes unless "DEV 13433" is marked next to the cell stack P/ N. We have not changed the final rule in this regard. \n\nRequest To Allow Compliance With Maintenance Records \n\n\tUAL also requests that if Model 747-400 series airplanes are not allowed to be removed from the requirements of the second SNPRM as requested above, then the only regulatory actions imposed on operators should be limited to demonstrating compliance through their own maintenance records. \n\tWe partially agree with the commenter. In paragraph (c) of this final rule we do allow a review of airplane maintenance records to determine the P/N of the flight deck humidifier instead of doing the inspection. We have determined that a review of the maintenance records is also acceptable if it can be determined that the flight deck humidifier is not installed. We have revised paragraph (c) to state that "instead of inspecting the flight deck humidifier, a review of airplane maintenance records along with any other applicable data is acceptable if the P/N of the flight deck humidifier can be positively determined from that review or if it can be positively determined that the flight deck humidifier is not installed on the airplane." \n\nRequest To Allow Equivalent Blanking Plate Installation \n\n\tUAL also requests that we consider the blanking plate installation and humidifier system deactivation done in accordance with Boeing Service Bulletin 777-21-0087, dated June 17, 2004; and Hamilton Sundstrand Service Bulletin 816086-21-01, dated March 15, 2000; as equivalent to the blanking plate installation done in accordance with Boeing Alert Service Bulletin 777-21A0048, Revision 2, dated July 14, 2005 (specified in paragraph (f) of the second SNPRM). \n\tThe commenter states that it has deactivated the humidifiers and replaced the cell stacks with blanking plates on all Group 7 airplanes identified in Boeing Alert Service Bulletin 777-21-0048, registration numbers 09UA and 16UA-29UA, by doing the actions in Boeing Service Bulletin 777-21-0087 and Hamilton Sundstrand Service Bulletin 816086- 21-01. The commenter also notes that the airplane having registration number 09UA, was delivered with a deactivated humidifier and only needed modification by doing the blanking plate installation per Hamilton Sundstrand Service Bulletin 816086-21-01. \n\tWe agree with the commenter. We have revised paragraph (f)(2)(ii) of this final rule to give credit for airplanes on which the replacement and deactivation are done in accordance with Boeing Service Bulletin 777-21-0087 and Hamilton Sundstrand Service Bulletin 816086- 21-01 for those Group 7 airplanes listed in Boeing Service Bulletin 777-21-0087, dated June 17,2004. \n\tWe have also determined that a review of the maintenance records is acceptable instead of the inspection specified in paragraph (f) of this final rule if it can be determined that the flight deck humidifier is not installed. We have revised paragraph (f) to state that "instead of inspecting the flight deck humidifier, a review of airplane maintenance records along with any other applicable data is acceptable if the P/N of the flight deck humidifier can be positively determined from that review or if it can be positively determined that the flight deck humidifier is not installed on the airplane." \n\nConclusion \n\n\tAfter 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. \n\nCost ImpactThere are approximately 176 airplanes of the affected design in the worldwide fleet. The FAA estimates that this AD affects 29 airplanes of U.S. registry. The cost per airplane ranges between $390 and $6,248 per airplane, depending on the actions chosen by the operator. The fleet cost estimate does not exceed $181,192. \n\nESTIMATED COSTS\n\nModel/series\nAction\nWork Hours\nHourly Rate\nParts Cost\nCost per airplane\n747-400, 777-200, 777-300\nInspect flight deck humidifier for P/N and inspect flight deck humidifier cell stack for P/N.\n1\n$65\n$0\n$65\n747-400\nReplace cell stack with new or supplier-tested cell stack\n3\n65\n5,100\n5,295\n747-400\nReplace cell stack with blanking plate and deactivate humidifier.\n5\n65\n0\n325\n777-200, 777-300\nReplace cell stack with blanking plate\n3\n65\n0\n195\n777-200, 777-300\nReplace cell stack with new or supplier-tested cell stack\n3\n65\n6,053\n6,248\n777-200, 777-300\nReplace blanking plate with supplier-tested cell stack\n1\n65\n6,053\n6,118\n\nThe cost impact figures discussed above are 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. \n\nAuthority for This Rulemaking \n\n\tTitle 49 of the United States Code specifies the FAA's authority to issue rules on aviation safety. Subtitle I, Section 106, describes the authority of the FAA Administrator. Subtitle VII, Aviation Programs, describes in more detail the scope of the Agency's authority. \n\tWe are issuing this rulemaking under the authority described in Subtitle VII, Part A, Subpart III,Section 44701, "General requirements." Under that section, Congress charges the FAA with promoting safe flight of civil aircraft in air commerce by prescribing regulations for practices, methods, and procedures the Administrator finds necessary for safety in air commerce. This regulation is within the scope of that authority because it addresses an unsafe condition that is likely to exist or develop on products identified in this rulemaking action. \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\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\nAccordingly, 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\n1. The authority citation for part 39 continues to read as follows: \n\n\tAuthority: 49 U.S.C. 106(g), 40113, 44701. \n\nSec. 39.13 (Amended) \n\n2. Section 39.13 is amended by adding the following new airworthiness directive: