Airworthiness Directive · Amendment 39-15421 · Boeing Model 737-200 Series Airplanes
Boeing Model 737-200 Series Airplanes
This AD applies to Boeing Model 737-200 series airplanes, line numbers 814 through 826 inclusive, certificated in any category.
We are adopting a new airworthiness directive (AD) for certain Boeing Model 737-200 series airplanes. This AD requires repetitive inspections to detect cracking of the support fittings of the Krueger flap actuators, and corrective actions if necessary. This AD also requires eventual replacement of any existing aluminum support fitting on each wing with a steel fitting, and modification of the aft attachment of the actuator. Doing these actions terminates the repetitive inspection requirements. This AD results from reports of cracking due to fatigue and stress corrosion of the support fittings of the Krueger flap actuator. We are issuing this AD to prevent cracking of the support fittings, which could result in fracturing of the actuator attach lugs, separation of the actuator from the support fitting, severing of the hydraulic lines, resultant loss of hydraulic fluids, and consequent reduced controllability 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.
Within 12 months after the effective date of this AD, do a high frequency eddy current (HFEC) inspection to detect cracking of the support fittings of the Krueger flap actuator on each wing, in accordance with the Accomplishment Instructions of Boeing Special Attention Service Bulletin 737-57-1129, Revision 3, dated March 19, 2007.
(1) If no cracking is detected, repeat the inspection thereafter at intervals not to exceed 3,000 flight hours until the terminating action required by paragraph (g) of this AD is accomplished.
(2) If any cracking is detected, before further flight, do the replacement and modification specified in paragraph (g) of this AD.
Within 60 months after the effective date of this AD: Replace any existing Krueger flap actuator aluminum support fitting on each wing with a steel fitting, and modify the actuator aft attachment, in accordance with the Accomplishment Instructions of Boeing Special Attention Service Bulletin 737-57-1129, Revision 3, dated March 19, 2007. Doing this replacement and modification terminates the repetitive inspection requirements of paragraph (f) of this AD.
As of the effective date of this AD, no person may install on any airplane any aluminum support fitting (actuator support assembly) identified in the “Existing Part Number” column of paragraph 2.C. of Boeing Special Attention Service Bulletin 737-57-1129, Revision 3, dated March 19, 2007.
(i) Actions done before the effective date of this AD in accordance with the service bulletins listed in Table 1 of this AD, are acceptable for compliance with the corresponding requirements of this AD.
| Boeing service bulletin | Revision level | Date |
|---|---|---|
| 737-57-1129 | 1 | Oct. 30, 1981. |
| 737-57-1129 | 2 | May 28, 1998. |
