The FAA has issued two Airworthiness Directives (ADs) that affect several models in the Cessna and Piper GA fleets.

One AD mandates replacement and repetitive inspection of an elevator-trim component on some Cessna twin-engine models, while the other expands the applicability of an inspection requirement to additional Piper single-engine airplanes in the PA-28 line. Both ADs take effect April 26.

AD 2016-07-21 requires replacement and repetitive inspections of the hardware securing the elevator trim push-pull rod. The AD pertains to the following Cessna (Textron Aviation) twin-engine models: 310 through 310R, E310H, E310J, T310P through T310R, 310J-1, 320 through 320F, 320-1, 335, 340, 340A, 401 through 401B, 402 through 402C, 411, 411A, 414, 414A, and 421 through 421C airplanes.

“This AD was prompted by lessons learned in accident investigation support, analysis of past accidents, and NTSB determinations of probable cause,” the FAA said. “That information indicates that following the loss of the attachment hardware connecting the elevator trim tab actuator to the elevator trim tab push-pull rod, the elevator tab may jam in a position outside the normal limits of travel.” About 5,088 Cessna twins are estimated to be affected.

AD 2016-07-24 requires inspection of the right wing rib at wing station 140.09 for cracks and necessary corrective action be taken. This AD supersedes a previous AD by extending to additional serial numbers of certain PA-28-161, PA-28-181, and PA-28R-201 airplanes.

The AD retains the requirements of AD 2015-20-13, and was prompted by reports that additional airplanes have been found with the same cracks. The FAA estimates that 720 U.S.-registered aircraft are added to this AD’s applicability.