442nd Fighter Wing Public Affairs
5/8/2009 - WHITEMAN AIR FORCE BASE, Mo. -- In the early days of aviation, pilots had very few options and very little hope of surviving if they had to leave their aircraft in flight. Typically, the outcome was fatal.
Over the years, as technology developed, those chances improved as first, parachutes were developed, and later, in the case of military aircraft, ejection systems came on line.
Today, if the worst happens and an A-10 pilot has to eject, he or she can feel confident that the aircraft's egress system will safely, and quickly, take them out of danger.
At the heart of the A-10 egress system is the Advanced Concept Ejection Seat II.
Better known as ACES II, the seat was developed in the early 1970s as a way to standardize to one type of seat. One benefit to having a standardized seat was a reduction in training for both pilots and maintainers, who previously needed to be trained in a variety of seats. Another design goal was to have better performance in a variety of conditions, such as low or adverse altitudes, including "Zero-Zero", the lowest point in the ejection envelope or zero altitude, zero speed.
Origianlly maunfactured by McDonnell-Douglas Corporation, and later Weber Aircraft Company, more than 8,000 seats have been made.
According to the official Air Force records, the seat has had a success rate of 94.4 percent in envelope, and 89.9 percent when including out of envelope ejections.
While much of that success rate is due to the design of the system, even the best designed product is only as good as the maintenance it routinely receives.
In the case of the 442nd Fighter Wing, the ACES II seats here are among the best maintained.
Under the guidance of Senior Master Sgt. Kevin McMenemy, 442nd Egress Flight chief, the shop has a highly-trained cadre ... most seven-level qualified ... of Air Reserve Technicians and traditional reservists.
"We have to go to a six-week tech. school down a Sheppard Air Force Base," said Staff Sgt. Chuck Wilson, an egress systems technician with nine years maintaining the seat. "Then its about 15 months of on-the-job training to complete a five-level and 12 more months to get a seven-level."
During that upgrade training the technicians refine their skills on the 180-pound seat, removing them from the A-10s when they come in to the phase inspection area of the five-bay hangar, bringing them into the shop for maintenance and returning them to the aircraft before it's ready to return to service.
A critical and potentially dangerous part of the Egress troops work deals with the 17 explosives on the aircraft - the rocket catapault that fires at 5,000 pounds of thrust for .55 seconds, which propels the seat and pilot away from the aircraft.
One unique component is the seat-trajectory and pitch-attitude control, or STAPAC, package. It is designed to keep the seat flying in a straight trajectory. The package includes a rocket, which produces more than 1,000 pounds of thrust for one half of a second. The seat also holds a the pilot's parachute and a survival kit.
"When the pilot pulls the (ejection) handles." Sergeant Wilson said, "just 1.8 seconds later, they are fully ejected underneath the canopy floating back to the ground."
Even with the explosives, however, Sergeant Wilson said the ACES II is one of the safest around.
As seat maintenance needs to be performed, Egress troops remain busy. At any given time there are two to four seats in the shop being worked on.
"We always have to monitor the time change requirements," Sergeant Wilson said.
Staff Sgt. Anthony Bonham, one of the newer egress technicians, came to the 442nd after an active-duty stint with the 509th Bomb Wing. While both aircraft use the ACES II system, Sergeant Bonham said he likes working on the A-10.
"The seat was about the same," Sergeant Bonham said. "But what you have to do to pull the seat; the A-10 is a lot simpler."
The shop's goal is 100-percent accuracy in maintenance and it's something they take very seriously. A pilot's life can depend on the fact that, when needed, the seat will operate as advertised.
Staff Sgt. Anthony Bonham, an Air Force reservist with the 442nd Maintenance Squadron's Egress shop, carefully swings an ACES II ejection seat into position for installation into A-10C 78-0655 from the 303rd Fighter Squadron at Whiteman AFB, Missouri. Sergeant Bonham and the other reservists in the Egress shop maintain the ejection seats to help ensure pilots have a way to safely and effectively leave the aircraft in the event of an emergency. (U.S. Air Force photo by Master Sgt. Bill Huntington) Hi-res
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