COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 105 CIVIL AVIATION SAFETY AUTHORITY
SCHEDULE OF AIRWORTHINESS DIRECTIVES
Beechcraft 18 Series Aeroplanes
AD/BEECH 18/17
Amdt 4
Aircraft Modification, Inspection and Retirement
9/81
Applicability: All models Beech 18 Series.
Requirement: 1. In accordance with a scheme approved by the Secretary, modify the wing by installing an external strap reinforcement covering the lower cap of the main spar welded truss over both the centre-section and outer-wing.
Note 1: The following strap modifications are currently approved by the Secretary:
- Dee Howard Company, San Antonio, Texas-Scheme holding United States Supplemental Type Certificates - SA832SW and SA895SW in combination.
b. Hamilton Aircraft Company, Tucson, Arizona-Scheme holding United States Supplemental Type Certificate - SA2000WE.
2. Inspect the following areas using visual methods together with dye penetrant or magnetic particle methods, to detect fatigue cracking of the wing main spar truss lower cap. All welded joints in the vicinity of these positions shall be inspected.
- Wing Stations 0, 28, 44, 61 and 81.
b. Both sides of the centre-section to outer wing joint.
c. Each welded joint area in the outer wing including the welded bosses for the horizontal through bolts.
d. The outer wing joint between the welded truss and the aluminium alloy riveted structure.
3. a. For aeroplanes incorporating the Dee Howard Company STCs SA832SW and SA895SW in combination visually inspect in situ the external strap modification for cracks and/or corrosion, using appropriate optical aids. Pay particular attention to welds at end fittings, bends in the strap, forward and aft edges and the strap sections normally covered by the locating clips.
3. b. For aeroplanes incorporating the Hamilton Aircraft Company STC SA2000WE, visually inspect in situ the external strap modification for cracks and/or corrosion.
4. Retire aircraft from service.
COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 105 CIVIL AVIATION SAFETY AUTHORITY
SCHEDULE OF AIRWORTHINESS DIRECTIVES
Note 2: This Directive is aimed at modifying and inspecting the wing so that a measure of main spar fail-safe capability is achieved. In order to maintain the necessary full limit load residual strength in the event of a spar truss tube failure it should be noted that the maximum gross weight of any Beech 18 variant is limited to 4490 Kg (9900 lb.). This does not endorse weight increases for aircraft certificated below this figure.
Compliance: 1. Before issue of Certificate of Airworthiness.
2. At intervals not exceeding 300 hours time in service.
3. a. At intervals not exceeding 100 hours time in service.
3. b. At intervals not exceeding 300 hours time in service.
4. Before exceeding 10000 hours time in service after strap modification or before 20000 hours time in service after manufacture, whichever occurs first.
Background: In service failure of a modification strap has occurred in an overseas aeroplane due to stress corrosion cracking emanating at edge of strap.