Defective Fuel Injection Systems Put Thousands of Small Aircraft at Risk


Thousands of small airplanes flown throughout the United States are at risk of engine failure due to a recently discovered defect in their fuel injection systems.

The defect involves servo plug gaskets in fuel injection systems manufactured by Precision Airmotive LLC, which have been found to shrink from engine heat, causing screws to lose torque and injector assembly components to clamp-up. This leads to a loss of engine power or complete engine failure.

Upon learning of the defect, which is believed to have been a contributing cause to engine failure in at least two recent crashes, the Federal Aviation Administration (FAA) has issued an Air Worthiness Directive that effectively grounds all aircraft with the defective fuel injection systems until the screws can be inspected.

The FAA directive requires immediate inspection of all planes with RSA-5 or RSA-10 servos that have had a new, rebuilt, overhauled or repaired engine and / or servo installed since August 2006, to determine if the brass regulator plug is loose. The inspections must be conducted by a licensed FAA mechanic.

In its March 12, 2008 directive, the FAA noted it has received 18 reports in which the gaskets had shrunk from engine heat, causing the servo plugs to vibrate out.

Two recent incidents involving Precision Airmotive RSA-10ED1 fuel-injection servos on Lycoming IO-540-K engines in Piper Saratoga/6X aircraft have involved brass hex plugs with damaged threads that were hanging from their safety wires and out of their holes. One incident resulted in an off-airport landing that considerably damaged the involved aircraft.

“This condition, if not corrected, could result in a substantial loss of engine power and subsequent loss of control of the airplane,” the FAA directive notes.

Ladd Sanger, an FAA-licensed commercial airplane pilot who leads the aviation practice in Slack & Davis’ Dallas law office, says Precision’s defective servo gaskets pose a serious threat to many small aircraft owners and operators.

“These fuel-injection systems are common in thousands of airplanes – a significant percentage of the general aviation aircraft manufactured in the past 20 years,” Sanger said.

“Nearly the entire Piper piston-engine product line, as well as Cessna 206s and Cessna 172s manufactured since 1998 employ these systems,” he said. “We’re talking about a very significant number of airplanes that are at risk.”

Sanger, who has litigated numerous international and domestic airline cases, as well as military and general aviation crash cases, said he is aware of at least 40 inspections indicating loose plugs or regulator plates since the FAA issued its Air Worthiness Directive on March 12.

Sanger has litigated cases involving the Precision RSA-10 servo and had worked with a team of experts that pointed out the problem of screws in the servo losing torque to Precision in litigation years before the FAA and Precision finally acknowledged the problem.

“There have been at least two recent crashes where the servo plug was found dangling from the safety wire,” Sanger added. “Clearly, this is a systemic problem that could affect many, many airplanes. I’m glad to see the FAA is doing something about it.”