AGMA 13FTM13

Abstract

Several gear failure cases and lessons learned in thedevelopment phase of aircraft high lift actuation systems arepresented, including leading edge geared rotary actuators, andtrailing edge geared rotary actuators, sector gears and pinions,and offset gearboxes. The high lift system of an aircraft, whichcontains trailing edge flaps and/or leading edge slats, increaseslift for takeoff, controls flight during cruise, and reduces speedwhile increasing lift for shorter landing distance.

Many of these components contain highly loaded gears to increasethe power to weight ratio. Because of requirements on weight orenvelope and consideration of cost, the gears are always designedto the limit with reasonable margins of safety in a high liftsystem. The structure which supports the gears is limited in sizeand simplified, and the gear material and heat treatment areselected for easy manufacturing. Therefore, when misalignmentand/or deflection of the gears are large enough to cause reductionin tooth contact area, the stress on gears becomes large enough tocause damage. The failure modes can be classified as spalling orpitting at the location of concentrated loads. Most of the problemscan be resolved by providing correct lead modification to alleviatethe concentrated loading, while some need increase of the geardiameters, design modifications, or introduction of materials withhigher allowable.

Edition:

13

Published:

09/01/2013

Number of Pages:

15

File Size:

1 file , 610 KB