AD 63-10-03 ACTIVE

63-10-03 GENERAL DYNAMICS/CONVAIR: Amdt. 562 Part 507 Federal Register May 7, 1963. Applies to All Model 340 and 440 Aircraft.

Compliance required as indicated.

To detect certain wing lower skin fatigue cracks at the earliest possible time and to prevent their growth to an unsafe length, accomplish the following:

(a) For aircraft with 15,000 hours' or less time in service as of the effective date of this AD, prior to the accumulation of 15,100 hours' time in service and thereafter at periods not to exceed 1,000 hours' time in service from the last inspection, until the accumulation of 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 close visual inspection of that area for any indication of wing skin cracks. After the accumulation of 20,000 hours' time in service and before the accumulation of 20,500 hours' time in service accomplish the cleaning and inspection required by this paragraph and thereafter perform the cleaning and inspection at periods not to exceed 500 hours' time in service from the last inspection. If cracks are found accomplish (e), (f) or (g).

(b) For aircraft with more than 15,000 hours and less than 20,000 hours' time in service as of the effective date of this AD, within the next 100 hours' time in service from the effective date of this AD, unless already accomplished within the last 900 hours' time in service and thereafter at periods not to exceed 1,000 hours' time in service from the last inspection, 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 close visual inspection of that area for any indication of wing skin cracking. After the accumulation of 20,000 hours' time in service and before the accumulation of 20,500 hours' time in service accomplish the cleaning and inspection required by this paragraph and thereafter perform the cleaning and inspection at periods not to exceed 500 hours' time in service from the last inspection. If cracks are found accomplish (e), (f), or (g).

(c) For aircraft with 20,000 hours' time in service or more as of the effective date of this AD, within the next 100 hours' time in service from the effective date of this AD unless already accomplished within the last 400 hours' time in service and thereafter at periods not to exceed 500 hours' time in service from the last inspection, 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 close visual inspection of that area for any indication of wing skin cracking. If cracks are found accomplish (e), (f), or (g).

(d) For aircraft that have no wing lower skin cracks in the area described in (a), (b), or (c) the specified 500 hours periodic re-inspection time may be increased to 1,000 hours' time in service when the aircraft has been modified in the following manner: 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 found, install a close tolerance -8 rivet or a 1/4-inch bolt. If cracks are found accomplish (e), (f), or (g) as applicable.

(e) Aircraft with wing skin cracks less than 6 inches in length, unless already repaired in the manner prescribed in (g) or (h) shall be modified and inspected as follows:

(1) 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 and at periods thereafter not to exceed 100 hours' time in service conduct an internal inspection inthe manner prescribed in (a), (b), or (c) as applicable. If during any such 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 again be stop drilled and the 100-hour periodic inspections continued. When a crack reaches the 2-inch limit, the provisions of (e)(2) will apply.

(2) For wing skin 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 inspection of the stop drilled crack must be conducted in the manner prescribed by (a), (b), or (c), as applicable, at periods not to exceed 100 hours' time in service. If during any such inspection, the crack is foundto have progressed beyond a stop drill hole, but the total length remains less than 3 inches, the crack may again be stop drilled and the 100-hour periodic inspections and speed restrictions continued. When a crack reaches the 3-inch limit, the provisions of (e)(3) will apply.

(3) 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 per Convair Service Engineering Report 6820-340-47B/440-47B dated January 15, 1963, or an FAA Western Region, Engineering and Manufacturing Branch approved equivalent installation, 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. The cleaning and internal inspection prescribed in (a), (b), or (c), as applicable, shall be conducted at periods not to exceed 500 hours' time in service. At a time when further wing skin cracking is found in the area described in (a), (b), or (c) but in no case more than 1,000 hours' time in service from the aforementioned temporary repair, repair the aircraft per (g).

(f) An aircraft with wing skin cracks less than 2 inches in length, including stop drill holes, unless repaired per (g), may be permanently repaired by installing internal reinforcement plates inboard and outboard of Station 8 per Convair Service Engineering Report 6820-340- 47B/440-47B dated January 15, 1963, or an FAA Western Region, Engineering and Manufacturing Branch approved equivalent installation.

(g) Aircraft with wing skin cracks greater than 6 inches in length shall be repaired prior to further flight. The repair must be in accordance with Convair Service Engineering Report 6820-340-47B/440-47B dated January 15, 1963 (340-1610922-7P and/or -8P external plate, external straps and internal plates inboard ofStation 8), or an FAA Western Region, Engineering and Manufacturing Branch approved equivalent installation.

(h) The requirements of this AD do not apply to aircraft repaired in the manner prescribed in (f) or (g) before the effective date of this AD or if, prior to any wing skin cracking in the area described in (a), (b), or (c) the aircraft has been modified between stringers 6 and 10, in accordance with Convair Service Engineering Report 15-4-340-18/440-22 dated May 9, 1958, or an FAA Western Region, Engineering and Manufacturing Branch approved equivalent installation. Also, the periodic reinspections required by (a), (b), (c), and (e) may be discontinued, and the operating limitations and placard specified in (e)(2) and (e)(3) may be removed from any aircraft when it is repaired in the manner prescribed in (f) or (g) or if, prior to any wing skin cracking in the area described in (a), (b), or (c), the aircraft has been modified between stringers 6 and 10, in accordance withConvair Service Engineering Report 15-4-340-18/440-22 dated May 9, 1958, or an FAA Western Region, Engineering and Manufacturing Branch approved equivalent installation.

(i) Upon the request of the operator, an FAA maintenance inspector, subject to prior approval of the Chief, Engineering and Manufacturing Branch, FAA Western Region, may adjust the repetitive inspection intervals specified in this AD to permit compliance at an established inspection period of the operator if the request contains substantiating data to justify the increase for such operator.

(j) Any FAA engineering approved inspection method for detection of the wing lower skin cracks may be substituted for the cleaning and visual inspection specified in paragraphs (a), (b), (c), and (e).

(Convair Service Engineering Reports 6820-340-47B-440-47B dated January 15, 1963, and 15-4-340-18/440-22 dated May 9, 1958, pertain to this same subject.)

This directive effective May 7, 1963.

Revised November 26, 1963.