Products, Regulatory

Showdown Set on FAA Barrier Filter Policy

By James T. McKenna | July 6, 2016
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Look for industry leaders to square off with FAA officials in Texas tomorrow over a proposal to adopt more stringent procedures for certification of engine inlet barrier filters.

The agency is convening a meeting near Fort Worth Alliance Airport the morning of July 7 to discuss its proposed policy statement on certification of helicopter engine inlet barrier filters. 

“The purpose of the public meeting is for the FAA to hear the public's views and obtain information relevant to the policy,” the agency said May 25, adding that it will consider public comments previously submitted to it and those made at the “before making a final decision on issuance of the policy.”


But the two U.S. manufacturers of such filters, Aerometals and Donaldson Aerospace, fear the FAA’s focus is not on discussing the proposed policy’s merits but on implementing it. 

“The agency now seems poised to act quickly to implement” the policy, identified as PS-ASW-37/29-07,” Donaldson said in a widely distributed statement. “If the FAA proceeds as planned, it likely would be the beginning of the end for the development of engine-protecting IBFs for many helicopters operating today.”

The president of Aerometals, Rex Kamphefner, said the new policy is to implement his company and Donaldson “must exit the filter aftermarket business.”

Inlet barrier filters (or IBFs) are designed to keep dirt, dust, sand, foreign objects and other contaminants from entering a helicopter engine. IBFs can provide greater protection than traditional particle separator/inertial separator systems or foreign object debris (FOD) screens. 

IBFs are relied upon by operators flying from unimproved locations on firefighting, rescue and utility missions, and have been used widely by the U.S. military in operations in Iraq, Afghanistan and similar areas. 

The agency posted the proposed policy publicly on January 25. It had been floating around for years, according to numerous industry and FAA officials. Since January, the agency has been collecting public comments on the policy. (The deadline for comments is July 7 at midnight Eastern U.S. time.) 

The FAA says its purpose in drafting the policy is to fix a longstanding shortcoming. While the use of helicopter IBFs “is becoming a common occurrence,” the proposed policy states, rotorcraft airworthiness standards and certification guidance material in advisory circulars “do not specifically address IBF installations.” What guidance that does exist has been captured in what are called Issue Papers written to cover specific certification projects. The FAA says, “This policy captures that guidance.”

IBF advocates argue the proposed policy does more than that. They say it establishes numerous new procedures and requirements, some of which are erroneous.

A major change concerns demonstrating the effect of an IBF’s installation on a helicopters power performance. A common technique for establishing that an IBF is not impairing performance today is to do regular power-assurance checks. 

But the proposed policy states performing periodic power-assurance checks “is not an acceptable means of compliance.” It stipulates that applicants for a supplemental type certificate covering an IBF installation “should provide adequate substantiation to account for the different installation losses with the IBF installed.” 

The policy goes on to note: “Some aspects of ground and flight testing may require direct assistance and information from the engine and airframe manufacturers, such as utilization of engine computer decks, installation effects, and flight test instrumentation.” 

However, engine and airframe OEMs have not always cooperated with the development of IBFs for their aircraft, forcing filter makers to compile engineering data on their own. 

Aerometals and Donaldson argue that the proposed policy fixes a problem that does not exist. Aerometals Kamphefner, citing numbers also quoted by Donaldson, said, IBFs “have accumulated 20 million flight hours, which have been bought and installed on 7,000 helicopters. There have been zero accidents. 

“Where, I ask you, is the safety problem?” Kamphefner said.

Donaldson argues that the FAA traditionally has relied on the Aviation Rulemaking Advisory Committee (ARAC) “to provide practical counsel and recommendations on new and existing regulations” and that the agency should stick to that approach on IBF certification changes, “not just for helicopter owners and operators, but for the public they serve.” 

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