Airworthiness Directive · Amendment 39-14586 · Boeing Model 747 Airplanes
Boeing Model 747 Airplanes
This AD applies to all Boeing Model 747-100, 747-100B, 747-100B SUD, 747-200B, 747-200C, 747-200F, 747-300, 747-400, 747-400D, 747-400F, 747SR, and 747SP series airplanes; certificated in any category.
The FAA is adopting a new airworthiness directive (AD) for all Boeing Model 747 airplanes. This AD requires the following actions for the drive mechanism of the horizontal stabilizer: Repetitive detailed inspections for discrepancies and loose ball bearings; repetitive lubrication of the ballnut and ballscrew; repetitive measurements of the freeplay between the ballnut and the ballscrew; and corrective action if necessary. This AD results from a report of extensive corrosion of a ballscrew in the drive mechanism of the horizontal stabilizer on a similar airplane model. We are issuing this AD to prevent an undetected failure of the primary load path for the ballscrew in the horizontal stabilizer and subsequent wear and failure of the secondary load path, which could lead to loss of control of the horizontal stabilizer and consequent loss of control of the airplane.
You are responsible for having the actions required by this AD performed within the compliance times specified, unless the actions have already been done.
Do all the applicable actions, including any applicable corrective action, specified in Work Packages 1, 2, and 3 of the Accomplishment Instructions of Boeing Alert Service Bulletin 747-27A2396, Revision 1, dated August 4, 2005. Do the actions at the applicable compliance time specified in Table 1 of paragraph 1.E. “Compliance” of the service bulletin; except, where the service bulletin specifies a compliance time relative to the original issue date of the service bulletin, this AD requires compliance relative to the effective date of this AD. Where the service bulletin specifies a compliance time relative to the delivery date of the airplane, this AD requires compliance relative to the date of issuance of the original standard airworthiness certificate or the date of issuance of the original export certificate of airworthiness. Do any applicable corrective action before further flight. Repeat the actions at the applicable repeat interval specified in Table 1 of paragraph 1.E “Compliance” of the service bulletin.
Note 1: Boeing Alert Service Bulletin 747-27A2396, Revision 1, dated August 4, 2005, refers to the airplane maintenance manuals (AMMs) in Table 1 of this AD as additional sources of service information for accomplishing the detailed visual inspections, lubrications, freeplay measurements, and corrective actions.
| Boeing AMM | Subject |
|---|---|
| 747-100/200/300 AMM | 12-21-19 |
| 747-100/200/300 AMM | 27-41-06 |
| 747-400 AMM | 12-21-19 |
| 747-400 AMM | 27-41-06 |
Initial inspections accomplished before the effective date of this AD in accordance with Boeing Alert Service Bulletin 747-27A2396, dated September 4, 2003, are considered acceptable for compliance with the corresponding action specified in this AD. For airplanes on which the drive mechanism of the horizontal stabilizer was replaced before the effective date of this AD with a drive mechanism that was not new or overhauled, and the detailed and freeplay inspections were not accomplished in accordance with Boeing Alert Service Bulletin 747-27A2396, dated September 4, 2003: Within 4,000 flight hours or 24 months after the effective date of this AD, whichever is first, accomplish the inspections, and perform any applicable corrective action before further flight, in accordance with Work Package 3 of the Accomplishment Instructions of Boeing Alert Service Bulletin 747-27A2396, Revision 1, dated August 4, 2005.
As of the effective date of this AD, no person may install on any airplane a horizontal stabilizer trim actuator unless it is new or has been overhauled in accordance with Boeing Alert Service Bulletin 747-27A2396, Revision 1, dated August 4, 2005 (which refers to the applicable overhaul manual); or has been inspected, lubricated, and measured in accordance with paragraph (f) of this AD.
