Engine Placement Stymies Current Regulations

The FAA has proposed a set of special conditions the Aviation Technology Group's upcoming Javelin 100 will have to meet prior to the issuance of a Type Certification, due to the placement of the aircraft's twin turbofan engines.

The reason? The FAA says current airworthiness regulations for Part 23 aircraft do not contain adequate safety standards for the side-by-side placement of the $2.795 million jet's Williams engines, inside the aft fuselage like an F-15. Current regs assume the engines are separated from each other on mounting attachments to the fuselage or wing.

The agency is concerned with the possibility a fire in one engine could spread to the other... as well as to a 280 gallon fuel tank located forward of the engines, behind the cockpit. Critical control linkages and the plane's horizontal and vertical stabilizers are also nearby.

Current regulations also assume the engines will be in the pilots' field of vision, and a fire in one would not prevent the plane's pilot(s) from executing an emergency landing inside 15 minutes, before the flames break through the firewall. The FAA questions whether that same margin of safety would apply to the Javelin.

"Part 23 historically addressed fire protection on multiengine airplanes based on the assumption that the engines are sufficiently separated to essentially eliminate the possibility of an engine fire spreading to another engine..." the FAA writes in its request for comments on the proposed guidelines. "Title 14 CFR, part 23, did not envision the type of configuration of the Javelin Model 100 airplane."

To overcome the possibility of an engine fire spreading in a Javelin, the FAA proposes a "two-shot" fire extinguishing system, that would include features to isolate each fire zone from any other zone -- and the airplane -- to maintain isolation of the engines during a fire.

The comment period for the proposed special guidelines runs through February 7.

FMI: Read The NPRM, www.avtechgroup.com