Representatives of at least 10 helicopter firms told the FAA last month that proposed stricter guidelines for certification of inlet barrier filters are unneeded and would hike costs and hurt safety for rotorcraft flying in dirty, dusty environments.
As an example, AAR Airlift told FAA officials at a July 7 meeting in Fort Worth, Texas, that inlet barrier filters (IBFs) cut down on foreign object damage, over-temperature incidents and compressor stalls on engines on its aircraft flying in the Central African Republic and Niger.
Palm Bay, Florida-headquartered AAR Airlift, which operates medium and heavy helicopters around the world, cited 35 instances of unscheduled removals of engines unprotected by IBFs. It estimated that each incident cost the company $200,000 for maintenance and repair. In some cases, engines were removed after fewer than 60 running hours; one was pulled after 38.1 hr.
IBFs are designed to keep dirt, dust, sand, foreign objects and other contaminants from entering a helicopter engine. They can provide greater protection than traditional particle separator/inertial separator systems or foreign object debris (FOD) screens.
The FAA called the meeting to hear comments on the proposed policy, PS-ASW-37/29-07. It said that proposal is intended to fix a long-standing shortcoming in rotorcraft airworthiness standards and certification guidance, arguing that material does not specifically address IBF installations.
Critics of the policy, which has been in development for years, argue the track record of IBFs is proof that no changes are needed. IBF makers Aerometals and Donaldson Aerospace argue that IBFs have been installed on 7,000 helicopters that have accumulated 20 million flight hours collectively with no accidents attributed to them. The new policy would make development of new IBFs too difficult and costly for businesses to pursue.
Attendees at the meeting included representatives of Aerometals and Donaldson; helicopter manufacturers Bell Helicopter, Marenco Swisshelicopter and Sikorsky; AAR Airlift and another operator, Mountain Air Helicopters of Los Lunas, New Mexico; maintenance and support shops AeroBrigham of Decatur, Texas, and Advanced Helicopter Services of Woodland, California; and several other speakers. Aerometals President Rex Kamphefner said the proposed policy would “harm the safety of every pilot out there by not letting them have IBFs.”