AIRWORTHINESS DIRECTIVE
For the reasons set out in the background section, the CASA delegate whose signature appears below issues the following Airworthiness Directive (AD) under subregulation 39.001(1) of CASR 1998. The AD requires that the action set out in the requirement section (being action that the delegate considers necessary to correct the unsafe condition) be taken in relation to the aircraft or aeronautical product mentioned in the applicability section: (a) in the circumstances mentioned in the requirement section; and (b) in accordance with the instructions set out in the requirement section; and (c) at the time mentioned in the compliance section.
Kelowna Flightcraft (General Dynamics/Convair) Series Aeroplanes
AD/CONVAIR/22
Wing Lower Skin Inboard of Station 8
6/2006
Applicability:
Model 340 and 440 aircraft, and all such model aircraft converted to turbopropeller power.
Requirement:
1. For aircraft with 15,000 hours or less time in service: Clean the inside surface of the wing lower skin inboard of Station 8 in the vicinity of the second rivet from the outboard end of the short stringer in line with the wing access door in the wheel well, and conduct a detailed visual inspection of that area for any indication of wing skin cracks. If cracks are detected accomplish Requirements 4, 5, or 6. 2. For aircraft with more than 15,000 hours time in service and less than 20,000 hours time in service: Clean the inside surface of the wing lower skin inboard of Station 8 in the vicinity of the second rivet from the outboard end of the short stringer in line with the wing access door in the wheel well, and conduct a detailed visual inspection of that area for any indication of wing skin cracks. If cracks are detected accomplish Requirements 4, 5, or 6. 3. For aircraft with 20,000 hours time in service or more: Clean the inside surface of the wing lower skin inboard of Station 8 in the vicinity of the second rivet from the outboard end of the short stringer in line with the wing access door in the wheel well, and conduct a detailed visual inspection of that area for any indication of wing skin cracks. If cracks are detected accomplish Requirements 4, 5, or 6. For aircraft with no wing lower skin cracks detected in the specified inspection area, the inspection intervals may be increased to 1,000 hours time in service when the aircraft is modified as follows: Remove the 3/16-inch rivet located above where the cracks originate, enlarge the hole to 1/4-inch, and inspect the wing lower skin around the hole. If no wing skin crack is detected, install a close tolerance -8 rivet or 1/4-inch bolt. If cracks are detected, accomplish Requirements 4, 5, or 6, as applicable.
4. For aircraft with wing skin cracks less than 6-inches in length, unless already repaired in accordance with Requirements 6 or 7, modify and inspect as follows: a. For wing skin cracks less than 2-inches long, before further flight, stop drill each end of the crack with a 0.50-inch diameter drill. Repetitively inspect thereafter in accordance with Requirement 1, 2, or 3, as applicable. If during any inspection the crack is found to have progressed beyond a stop drill hole, but the total length remains less than 2-inches, the crack may be stop drilled and the 100-hour interval inspections continued. When a crack reaches the 2-inch limit, the provisions of Requirement 4.b. apply. b. For wing cracks between 2 and 3-inches in length, before further flight, stop drill each end of the crack with a 0.50-inch diameter drill and revise the airspeed limitations for the aircraft by reducing the never exceed speed (Vne) to 243 knots and the normal operating speed (Vno) to 217 knots and install a placard in the cockpit, in full view of the pilot stating the reduced speeds. An internal visual repetitive inspection of the stop drilled crack is to be accomplished in accordance with Requirements 1, 2, or 3, as applicable. If during any inspection the crack is found to have progressed beyond a stop drill hole, but the total length remains less than 3-inches, the crack may be stop drilled and the 100-hour interval inspections and speed restrictions continued. When a crack reaches the 3-inch limit, the provisions of Requirement 4.c. apply. c. For wing skin cracks between 3 and 6-inches in length, before further flight, repair the wing lower skin by installing internal reinforcement plates inboard of Station 8 in accordance with Convair Service Engineering Report No. 6820-340-47B/440-47B, dated 15 January 1963, and revise the airspeed limitations for the aircraft by reducing the never exceed speed (Vne) to 243 knots and the normal operating speed (Vno) to 217 knots and install a placard in the cockpit, in full view of the pilot stating the reduced speeds. An internal visual repetitive inspection is to be accomplished in accordance with Requirements 1, 2, or 3, as applicable. If during any inspection further cracking is detected, but in no case more than 1,000 hours time in service from above mentioned temporary repair, repair the aircraft in accordance with Requirement 6. 5. An aircraft with wing skin cracks less than 2-inches in length, including stop drill holes, unless repaired in accordance with Requirement 6, may be permanently repaired by installing internal reinforcement plates inboard and outboard of Station 8 in accordance with Convair Service Engineering Report No. 6820-340-47B/440-47B. 6. Aircraft with wing skin cracks greater than 6-inches in length must be repaired in accordance with Convair Service Engineering Report No. 6820-340-47B/440-47B.
7. The requirements of this Directive do not apply to aircraft repaired in accordance with Requirement 5 or 6 before the effective date of this Directive or if, before any wing skin cracking in the area described in Requirements 1, 2, or 3, the aircraft has been modified between stringers 6 and 10, in accordance with Convair Service Engineering Report No. 15-4-340-18/440-22 dated 9 May 1958. Also, the repetitive inspections required by Requirements 1, 2, 3, and 4 may be discontinued, and the operating limitations and placard specified in Requirements 4.b. and 4.c. may be removed from the aircraft when it is repaired in the manner specified in Requirement 5 or 6; and if, before any wing skin cracking in the area described in Requirements 1, 2, or 3, the aircraft has been modified between stringers 6 and 10, in accordance with Convair Service Engineering Report No. 15-4-340-18/440-22. Note: FAA AD 63-10-03 Amdt 562 Part 507 refers.
Compliance:
1. Before the accumulation of 15,100 hours time in service, and thereafter at intervals not to exceed 1,000 hours time in service, until the accumulation of 20,000 hours time in service. After the accumulation of 20,000 hours time in service, and before the accumulation of 20,500 hours time in service, accomplish Requirement 1 at intervals not to exceed 500 hours time in service. 2. Unless the initial inspection is already accomplished; within 100 hours time in service after 8 June 2006, unless accomplished within the last 900 hours time in service, and thereafter at intervals not to exceed 1,000 hours time in service. After the accumulation of 20,000 hours time in service, and before the accumulation of 20,500 hours time in service, accomplish Requirement 2 at intervals not to exceed 500 hours time in service. 3. Unless the initial inspection is already accomplished; within 100 hours time in service after 8 June 2006, unless accomplished within the last 400 hours time in service, and thereafter at intervals not to exceed 500 hours time in service. 4.a. At intervals not to exceed 100 hours time in service. 4.b. At intervals not to exceed 100 hours time in service. 4.c. At intervals not to exceed 500 hours time in service. 5. As specified in Requirement 5. 6. Before further flight. 7. As specified in Requirement 7.
This Airworthiness Directive becomes effective on 8 June 2006.
Background:
The FAA requires certain inspections and modifications to detect and correct wing lower skin fatigue cracking.
David Villiers
Delegate of the Civil Aviation Safety Authority 11 April 2006
