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AD/B747/359 - Flight Deck Humidifier
Boeing 747 Series AeroplanesBoeing 747 Series Aeroplanes
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Boeing 747 Series Aeroplanes
| AD/B747/359 | Flight Deck Humidifier | 9/2007 |
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| Applicability: | Boeing Model 747-400 series aeroplanes as identified in Boeing Service Bulletin747-21A2414, Revision 3, dated 12 May 2006. |
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| Requirement: | 1. For Model 747-400 series aeroplanes identified as Group 1 in Boeing Service Bulletin 747-21A2414, Revision 3:(a) Do the replacement specified in Requirement 1(b) or 1(c) 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 15 March 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 29 July 1999.Note 1: Boeing Service Bulletin 747-21A2414, Revision 3, specifies Group 1 as "all 747-400 aeroplanes with Hamilton Sundstrand flight deck humidifier 821486-01." The correct part number (P/N) for the humidifier is 821486-1.(b) 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.(c) Replace the cell stack of the flight deck humidifier with a blanking plate and, 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.Note 2: Boeing Service Bulletin 747-21A2414 Revision 3 refers to Boeing Service Bulletin 747-21-2405 Revision 4, as an additional source of service information for deactivating the humidifier.Note 3: Boeing Service Bulletin 747-21A2414 Revision 3 refers to Hamilton Sundstrand Service Bulletin 821486- 21-01, as an additional source of service information for the cell stack replacements. |
| 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 corresponding action specified in Requirement 1 of this AD.2. For Model 747-400 series aeroplanes identified as Groups 2 and 3 in Boeing Service Bulletin 747-21A2414, Revision 3: 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. Instead of inspecting the flight deck humidifier, a review of aeroplane 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 aeroplane.(a) 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 Requirement.(b) If P/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 aeroplane 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.(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 Requirement.(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 Requirement 1 of this AD.Inspections accomplished before the effective date of this AD in accordance with Boeing Alert Service Bulletin 747-21A2414, Revision 2, dated 7 July 2005, are considered acceptable for compliance with the corresponding action specified in Requirement 2 of this AD.3. Do not 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.Note 4: FAA AD 2006-21-05 dated 6 October 2006 refers. |
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