Aviation Maintenance Errors

Pilot error caused copter crash

The trouble started within two seconds of the helicopter's engine drive being disengaged from the rotors — the equivalent of putting a car transmission in neutral — in a test of the chopper's ability to "autorotate."

Pilots are trained to use the spinning momentum of the rotor and upward airflow to keep flying.

Instead, the Army OH-58D Kiowa Warrior quickly lost airspeed and plummeted from an altitude of 250 feet, according to an Army investigation. The two-seat chopper crashed at Wheeler Army Airfield, killing the pilots, Stanley Blane Hepfner, 29, and Jonathan Bryce Millward, 28, both chief warrant officers.

The accident investigation, obtained by the Star-Advertiser through the Freedom of Information Act, cites pilot error as the cause. The report says a drop in airspeed, a failure to abort the autorotation and a belated attempt to power back up sent the aircraft into a descent greater than 300 feet per minute into its own downwash.

"The pilots did not correct airspeed to stay within acceptable safety parameters," the report said.

The ill-fated flight on May 27, 2009, included a required test of the Kiowa's ability to autorotate, an emergency procedure in case the engine conks out in flight.

Civilian helicopter flight instructors say autorotation practice can be challenging and is a leading cause of hard landings.

Following the investigation, the 25th Combat Aviation Brigade modified standard operating procedures for Kiowa maintenance test flights, including changing the minimum altitude for recovery to 1,000 feet from 500 feet above ground level, officials said.

Jynnae Smedley just knows that she lost her brother, Millward, in the crash.

"I think we've accepted" that it was pilot error, the Idaho resident said. "We don't know which pilot made a mistake. We know that they were both excellent pilots, and we also are aware there's an awful lot to flying one of those helicopters. Just any slight mistake, obviously, can cause critical injury."

Although it was impossible to determine who was at the controls at the time of the crash, Hepfner was the "pilot in command," rated as a maintenance test pilot, and "was ultimately responsible for every aspect of operating the aircraft," the investigation said.

AIN Blog: Torqued: Maintenance Errors Could Be Fatal : AINonline

Some days I feel like Richard Clarke the fateful summer before the tragedy of 9/11, when his hair was all on fire as his warnings about the mounting threats by Al Qaeda against the U.S. fell on deaf ears. We all know how that turned out. I feel the same way about the mounting threats to maintenance: from inadequately trained technicians to insufficient oversight by operators and regulators (yes, that’s you, FAA) to the constant pressure to move aircraft as cheaply and quickly as possible. And, of course, the growing concern about the impact of fatigue on the quality of maintenance. The scientific data is beyond dispute: fatigue can and does cause mistakes, by mechanics as by everyone else.

Wherever I go these days, mechanics are tired. Those lucky enough to have kept their jobs are–on average–working longer hours and more days than ever. In part, this is because operators want to do more with less. It is cheaper for them to pay overtime than to hire more mechanics and have to pay them benefits. And mechanics who have had their pay cut from years of givebacks are eagerly taking on overtime and part-time work to maintain their standards of living–which in some cases means staying just two steps ahead of the bill collector.

Fatigue is just as insidious for mechanics as anyone else in transportation. Countless car, bus, truck and train crashes are caused by fatigued drivers. Airplane crashes caused by fatigued pilots grab headlines, but for some reason maintenance fatigue doesn’t grab headlines. Even the 1996 ValuJet accident in which 110 people died in a fiery plunge into the Everglades failed to highlight this critical fact. Could the improper maintenance on the oxygen generator canisters (mechanics failed to install safety caps as required by the maintenance manual) have been caused by over-tired mechanics? I certainly think so. 

An interesting fact that never received much public attention was that the repair station’s employees were on mandatory overtime that included extended workdays, seven days a week. Weeks and weeks of mandatory overtime was common at that facility at the time of the maintenance error that led to the improperly packed canisters being placed in the belly of the DC-9. The NTSB concluded that without the safety caps, the oxygen generators were primarily responsible for the resultant fire that ultimately brought down the aircraft.

Extended overtime is common today and has been since the cutbacks that followed 9/11. On top of the increased overtime, layoffs have resulted in a transient population of mechanics, unable to sell their homes and move, forced to live in makeshift arrangements to hold onto any maintenance work they can find. I was stunned to learn from a friend in Los Angeles that a sizeable parking area adjacent to LAX had become home to all manner of airline employees, including mechanics living in their vans and pickup truck campers. I shudder to think of the rest they ever get under such circumstances.

Managing maintenance error, a practical guide

Applied human factors in aviation maintenance

Human Reliability, Error, and Human Factors in Engineering Maintenance, With Reference to Aviation and Power Generation

Aviation Maintenance Technician's Handbook

Aviation Maintenance Technician Handbook