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AD/B747/367 - Lower Cargo Compartment Fire Extinguishing System - Time Delay Relays
Boeing 747 Series AeroplanesBoeing 747 Series Aeroplanes
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Boeing 747 Series Aeroplanes
| AD/B747/367 | Lower Cargo Compartment FireExtinguishing System - Time Delay Relays | 2/2008 |
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| Applicability: | Model 747-400, 747-400D and 747-400F series aeroplanes as identified in Boeing Special Attention Service Bulletin (SASB) 747-26-2281, dated 24 July 2006. |
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| Requirement: | 1. Carry out general visual inspection, in accordance with SASB 747-26-2281 of part number (P/N) TDH6103-1204, -1804 and -6003 time delay relay, as applicable, in the main equipment centre to determine if the relay was manufactured during a certain date range |
| 2. If, as a result of the Requirement 1 inspection, a relay manufactured during the date range specified in the SASB is found, replace the relay with a relay that was not manufactured during the specified date range, or with a relay that has been tested by the supplier and found to be unaffected by thermal expansion, in accordance with the SASB. | |
| 3. Time delay relay, P/N TDH6103-1204, -1804 or -6003, may not be installed on any aeroplane as a replacement spare, if the relay has a date code between 0000 and 0343 and does not have an additional date code with the letter "T.'' | |
| Later revisions of the above SASB, approved by the United States Federal Aviation Administration (FAA) as an Alternate Method of Compliance (AMOC) to FAA AD 2007-23-08, are considered acceptable for compliance with the equivalent Requirements of this Directive. | |
| Note: FAA AD 2007-23-08 Amdt 12524 refers. | |
| Compliance: | For Requirement 1 - Within 24 months after the effective date of this Directive. |
| For Requirement 2 - Within 30 days after finding a relay manufactured during the date range specified in the ASAB. | |
| For Requirement 3 - As of the effective date of this Directive | |
| This Airworthiness Directive becomes effective on 14 February 2008. |
| Background: | The FAA has advised of a report indicating that failure of a time delay relay in the electrical load management system (ELMS) panel of a Boeing Model 777 led to testing of other time delay relays at Boeing and at the supplier. Similar relays are also used in the cargo fire suppression system controlling when the secondary fire bottles discharge. |
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