A proposed airworthiness directive for possible cracks in the wing spar caps on many REVO, Inc. Lake amphibians involves a costly and unnecessary inspection requirement, the Seaplane Pilots Association and AOPA have told the FAA.
The proposed AD affects Lake models LA-4, LA-4A, LA-4P, LA-4-200, and Lake Model 250, including most of the popular Buccaneer and Renegade models. As proposed, the AD would require complete removal of wings, an inspection for cracks, and installation of a doubler kit on the wing spar.
"But the inspection requirement—which involves pulling the wings off the aircraft and will cost owners $2,000 to $4,000 per aircraft—is both superfluous and potentially damaging," said SPA Executive Director Michael Volk. "It calls for mechanics to pry the spar doubler away from the spar cap, which could cause more serious damage than the cracks they are trying to find. Then a doubler must be installed anyway, cracks or not."
Volk added that experienced mechanics have found the inspection ineffective. At least two FAA-certificated repair stations are developing procedures for applying the spar doublers without removing the wing from the aircraft.
The proposed AD was prompted by wing spar cap cracks found in seven Lake Buccaneers and Renegades, including one on which a spar doubler had already been installed. Subsequent research done by SPA in cooperation with Amphibians Plus, an FAA repair station in Bartow, Florida, showed 46 percent of Buccaneers and 92 percent of Renegades inspected had cracks in one or more of the four spar caps.
The proposed AD calls for complete removal and partial disassembly of wings, an inspection for cracks, and repair (regardless of whether cracks are found) with a doubler kit supplied by the Lake factory. If cracks are found anywhere except between the flange cutout radius and bolt hole of the spar cap, the damaged parts must be replaced.
Compliance would be required within 12 months or 50 hours in service for affected Lake aircraft with more than 500 hours total time. Renegade models with serial number 233 or higher would be exempt.
As part of research for the SPA and AOPA comments to the AD, Volk found that the lower-power Lake Buccaneers were less likely to suffer such spar cap cracks. In addition to the elimination of the inspection requirement, SPA and AOPA are recommending that the FAA relax the repair compliance time for Buccaneers.
"These recommendations would reduce the cost of compliance by 50 percent or more," said Volk, "as well as eliminating the risk of further damage during inspection, while ensuring reasonable precautions to prevent structural failure."
The Seaplane Pilots Association is an international, nonprofit membership association that has grown to more than 7,150 members in the United States, Canada, and 22 other countries. It works to protect the water flying rights of all seaplane pilots.
May 18, 2000