Piper PA-25 (Pawnee) Series Aeroplanes
AD/PA-25/40
Amdt 8
Wing Lift Struts 1/2000
Applicability: Model PA-25, PA-25-235, and PA-25-260 aircraft, serial numbers 25-1 through 25- 8156024.
Requirement: 1. Remove the wing lift struts in accordance with Piper Service Bulletin (SB) 528D, dated 19 October 1990, or Piper SB 910A, dated 10 October 1989, as applicable, and accomplish one of the actions in either Requirement 1.a., 1.b., 1.c., 1.d., or 1.e.:
- Inspect the wing lift struts for corrosion in accordance with the Instructions section in Part 1 of either SB 528D or SB 910A, as applicable.
(i) If no perceptible dents (as defined in the above referenced bulletins) are found in the wing lift strut and no corrosion is externally visible, before further flight, apply corrosion inhibitor to each strut in accordance with whichever of the above referenced bulletins that is applicable.
(ii) If a perceptible dent (as defined in the above referenced bulletins) is found in the wing lift strut or external corrosion is found, before further flight, accomplish one of the installations (and subsequent actions presented in each paragraph) specified in Requirements 1.c., 1.d., or 1.e.; or,
b. Inspect the wing lift struts for corrosion in accordance with an X-ray procedure approved by the Authority; or, in accordance with the Procedures and Requirements for Ultrasonic Inspection of Piper Wing Lift Struts attached as Appendix to FAA AD 99-01-05 Amdt 39-10972 (Appendix).
(i) If no corrosion is found that is externally visible and all requirements in the Appendix or X-ray procedure are met, before further flight, apply corrosion inhibitor to each strut in accordance with whichever of the above referenced bulletins that is applicable.
(ii) If external corrosion is found or if any of the requirements in the Appendix or X-ray procedure are not met, before further flight, accomplish one of the installations (and subsequent actions presented in each paragraph) specified in Requirements 1.c., 1.d., or 1.e.
c. Install original equipment manufacturer (OEM) part number wing struts (or FAA -approved equivalent part numbers) that have been inspected in accordance with the specifications presented in either Requirement 1.a. or 1.b. and are found to be serviceable according to the inspection requirements included in these Requirements.; or,
COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 105 CIVIL AVIATION SAFETY AUTHORITY
SCHEDULE OF AIRWORTHINESS DIRECTIVES
d. Install new sealed wing lift strut assemblies, part numbers as specified in SB 528D and SB 910A (or FAA-approved equivalent part numbers) on each wing as specified in the Instructions section in Part II of the above referenced bulletins. These sealed wing lift strut assemblies also include the wing lift strut forks; or,
Note 1: Installation of new sealed wing lift strut assemblies constitute terminating action for the inspection requirements of both Requirement 1 and 2 of this Directive.
e. Install F. Atlee Dodge wing lift strut assemblies in accordance with F. Atlee Dodge Installation Instructions No. 3233-1 for Modified Piper Wing Lift Struts (Supplemental Type Certificate (STC) SA4635NM), dated 1 February 1991.
2. If holes are drilled, in either one of the scenarios presented in paragraphs 2.a. and
2.b. to attach cuffs, door clips, or other hardware, inspect the wing lift struts using the procedures specified in Requirements 1.a. and 1.b. of this Directive:
- Wing lift strut assemblies installed in accordance with Requirement 1.d. of this Directive; or,
b. F. Atlee Dodge wing lift strut assemblies installed in accordance with Requirement .1.e. of this Directive.
3. Accomplish one of the following:
- Install “NO STEP” decal, Piper part number 80944-02, on each wing lift strut approximately 150 mm (6-inches) from the bottom of the struts in a way that the letters can be read when entering and exiting the aircraft; or,
b. Paint the statement “NO STEP” approximately 150 mm (6-inches) from the bottom of the struts in a way that the letters can be read when entering and exiting the aircraft. Use a minimum of 25 mm (1-inch) letters using a colour that contrasts with the colour of the strut.
Note 2: FAA AD 99-01-05 Amdt 39-10972 refers.
Compliance: 1. Within 1 calendar month after 31 December 1999 or within 24 months of the last inspection in accordance with Requirement 1 of the previous issue of this Directive, whichever occurs later.
1.a.(i) Reinspect at intervals not to exceed 24 calendar months, and accomplish any of the Requirement 1 actions of this Directive.
1.b.(i) Reinspect at intervals not to exceed 24 calendar months, and accomplish any of the Requirement 1 actions of this Directive.
1.c. Reinspect at intervals not to exceed 24 calendar months in accordance with the specifications presented in Requirements 1.a. or 1.b. of this Directive.
1.e. Reinspect at intervals not to exceed 60 calendar months in accordance with the specifications presented in Requirements 1.a. or 1.b. of this Directive.
2. At intervals not to exceed 24 calendar months.
3. Within 1 calendar month after 31 December 1999, unless already accomplished, and thereafter before further flight after the installation of any lift strut assembly.
This Amendment becomes effective on 31 December 1999.
Background: The manufacturer considers inspection of the lower bottom area of the struts critical.
The detection of internal corrosion in struts is in most cases difficult, and may not become apparent until advanced completely through the tube wall. Amendment 3 clarified assessment by a CAR35 Authorised Person of struts that have corrosion indicated radiographic inspection. Amendment 4 updated the reference document, and allowed new sealed struts as terminating action. The new strut also incorporates a redesigned strut fork.
Amendment 5 introduced a reduced corrosion inspection interval following two reports of excessive corrosion appearing within the 5 year interval. The requirement that the wing struts must be removed was also clarified, since service history revealed that water may enter the struts and resulting corrosion may go undetected if the struts are not removed. This has led directly to at least one fatal accident.
Amendment 6 corrected the compliance paragraph to allow 24 months since last X- ray inspection.
Amendment 7 introduced inspection of the strut upper end if the upper cuff fairing is attached by a screw. Reports were received of severe internal corrosion of wing struts at the upper cuff fairing screw attachment hole area.
Amendment 8 is issued to align this Directive with the requirements of a new Country of Origin FAA AD which supersedes AD 93-10-06; which was referenced in the previous issue of this Directive.
Amendment 7 of this Airworthiness Directive became effective on 18 July 1996. Amendment 6 of this Airworthiness Directive became effective on 22 June 1995.
The original issue of this Airworthiness Directive became effective on 5 October 1989.