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Aeronca has designed a conventional sheet metal fan cowl door for B737-300/400/500 series aircraft. These doors will provide superior maintainability at an acquisition price competitive to the cost of a major repair of existing composite doors. The weight of the new metal doors is nearly the same as the composite doors.
Design/Analysis
- Design is conventionally riveted sheet metal structure, completely interchangeable with existing doors and structures.
- Stiffened, stretched one piece skin.
- Circumfrential frames hinge to latch.
- Axial longerons between frames.
- Frames and longerons tied together with clips and fasteners.
- Vortex control device provision for either door.
- Finite Element Analysis used to verify design meets FAA requirements for STC.
- Materials used are conventional metals, well understood and easily repaired.
- Design drivers are low cost, long life, and reduced maintenance cost at no weight increase over current composite doors.
Manufacturing
- Skins are stretch formed, chem milled, trimmed, alodined, and primed.
- Stiffeners are formed, trimmed, alodined, and primed.
- Fittings are castings and forgings; machined deburred, and degreased.
- Other miscellaneous parts are machined from stock or formed from sheet metal.
- Total of 254 detail parts per engine set.
- Doors can be primed, painted to customer specification and decales applied.
Benefit
- Aluminum sheet metal design is much more durable than the existing composite doors.
- This will lead to a significant reduction in maintenance costs and aircraft downtime due to unscheduled removals and repairs.
- Design is FAA approved through both STC and PMA processes.
- Design is completely interchangeable with the current composite doors.
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