Guard crew talks about Sept. 9 four-engine rollback

  • Published
  • By Master Sgt. Bob Oldham
  • 189th Airlift Wing Public Affairs
LITTLE ROCK AIR FORCE BASE, Ark. --  Props 76, the call sign for an Arkansas Air National Guard C-130E, lifted off from the Little Rock Air Force Base runway Sept. 9 headed out for a three-hour proficiency flight for the crew, but what started as a training mission took a turn for the worse seconds after takeoff.

As the Hercules' propellers churned through the air toward the base perimeter, all four engines lost power -- from 15,000 inch-pounds of torque to 10,000 inch-pounds of torque -- causing the empty cargo aircraft to stop climbing into the clouds that overcast day and level off.

"You just don't see malfunctions that affect all four motors," Maj. Dean Martin, the 154th Training Squadron instructor pilot and aircraft commander on the mission, said as he reflected back on the flight.

At 800-1,000 feet over primarily wooded land, the crew didn't know it at the time, but they had only a few seconds to avert potential catastrophe.

Sitting in the right seat was Lt. Col. Rich McGough, Props 76 co-pilot who is also an instructor pilot in the squadron. Following his checklist procedures, he turned off the auxiliary hydraulic pump after the aircraft lifted off. Just after the colonel flipped the switch, the major noted that his vertical velocity indicator and collision avoidance system "went black." Both are on the same display in the cockpit.

"The auxiliary pump is the largest load on our electrical system," Major Martin said.

The flight engineer, Master Sgt. Doug McGroarty, switched the aircraft propellers to mechanical governing and turned the temperature datum system to null. That action, officials say, kept all four engines from flaming out, which could have resulted in a flaming heap of wreckage off the west end of the base's runway.

The temperature datum system controls the amount of fuel to the engines based on several engine parameters. Depending on the throttle position, the actual turbine inlet temperature, and the desired turbine inlet temperature the temperature datum system will send fuel or reduce the amount of fuel to each engine.

As soon as the flight engineer switched the system to null - essentially manually overriding the system - engines two, three and four roared back to life.

"The Rolls Royce engine rep on base said, 'Reducing the power would have caused all four engines to flame out,'" Major Martin explained.

Failing to take manual control of the engines would have also caused a flame out within eight to 10 seconds, Sergeant McGroarty said.

"When Doug brought the air turbine motor back online, No. 1 came back," the Major said.

The crew then flew an uneventful 12 minutes to the north and east and then back to the runway from the east. 

The cargo aircraft touched down and glided 7,000 feet down the 12,000-foot runway before turning onto the taxiway. Under normal conditions, the aircraft could stop shorter, but the crew was hesitant to turn the auxiliary pump back on. They were also hesitant to reverse the engines. They knew they had plenty of runway and were willing to use as much as they needed. 

The aircraft, a 1963 model, was impounded by maintenance for about two weeks as technicians and specialists studied and evaluated the cause. The culprit was a contact on a three-phase electrical bus that failed in one of the phases. Unfortunately for the crew of Props 76, it was on the essential bus, which runs several key components in the cockpit. 

"At the time, it didn't seem like it was that big of a deal," the flight engineer said. 

He said he's been more scared in previous in-flight emergencies, such as when he experienced a fire in the cockpit. Another hair-raising emergency was when an engine blew up on the wing. 

With a combined 13,100 hours of flying time between the three of them, he credited flying with a pair of experienced pilots as one of the reasons they were able to land safely on the ground. Major Martin has more than 4,200 hours in the air, Colonel McGough has more than 4,700 and Sergeant McGroarty has more than 4,200. 

But, he said, it goes deeper than that. "We've flown together for 12 years," he said of his relationship with Major Martin. "We flew together in the 50th [Airlift Squadron], 53rd [Airlift Squadron] and the 189th [Airlift Wing]." 

Today, the aircraft is back in service, and the crew members are back in the air training students. 

To alert others in the Air Force who fly the C-130, the wing's chief of safety generated an Air Force Safety Automated System report, coding the incident as one that has "high accident potential." That coding notified by e-mail each C-130 flight safety officer around the Air Force of the incident so that they can brief their crews to be on the lookout for a similar scenario.