The US Air Force (USAF) has begun an immediate action Time Compliance Technical Order (TCTO) on the F-22 Raptor's Emergency Oxygen System (EOS) to ensure full functionality in the wake of its increased usage under current operating procedures.
USAF pilots operating the F-22 experienced performance abnormalities on some of the EOS activations, which were analysed and corrective measures validated and verified.
The EOS is a self-contained, pilot-activated backup liquid oxygen system mounted on the jet's ejection seat and designed for use during main life-support system failure.
The EOS is a precautionary measure to protect pilots when they are faced with air supply problems.
The radar-evading F-22 Raptors have been barred from flying above 25,000ft since January 2011 following the crash of a jet in Alaska during a training flight as well as reports about pilots facing oxygen-related problems while flying the aircraft.
The fleet resumed flight operations in September 2011 following a four-and-a-half month grounding after mitigating the risk factors associated with the aircraft's oxygen system.
The F-22A Raptor is a supersonic, advanced tactical jet powered by dual F119-100 Pratt & Whitney engines, and is designed for stealth and greater cruise speed and agility. The aircraft has been used by the USAF since December 2005.
It features a radar warning receiver, information and electronic warfare systems, intra-flight data link, joint tactical information distribution system (JTIDS) link, and an identification friend system.
The aircraft, designed to replace the F-15, is armed with AIM-120A and AIM-120C AMRAAM missiles and two 1,000lb GBU-32 joint direct attack munitions (JDAM).
The USAF currently operates about 175 Raptors and is scheduled to receive new F-22s from Lockheed Martin.
Image Caption:The F-22A Raptor is a supersonic, advanced tactical fighter jet designed for stealth and greater cruise speed and agility.