Wednesday, October 21, 2015

The Federal Aviation Administration Wants New Helicopters to Have Crash-Resistant Fuel Tanks

U.S. aviation regulators plan to require all newly built helicopters to have crash-resistant fuel tanks to cut the risks of leaks and deadly fires after accidents as part of the broadest effort in decades to improve rotor-aircraft safety.

The Federal Aviation Administration asked an advisory committee to draft new regulations requiring the technology, according to a Sept. 28 letter sent to the National Transportation Safety Board and posted on the agency’s website.

That marks a significant shift on a controversial safety issue that has been linked to more than 200 civilian deaths since 1994. The U.S. Army has cut casualties from fires after helicopter crashes with the use of bladder-like fuel tank linings developed during the Vietnam War, but some operators and manufacturers argued that such technology was too expensive and would hamper operations.

“It is going to be extremely difficult and expensive to figure out how to incorporate it into an existing design,”  Walter Desrosier, the vice president for engineering and maintenance at the General Aviation Manufacturers Association trade group, said in an interview.

The FAA asked the industry panel, called the Aviation Rulemaking Advisory Committee, to explore ways to better protect helicopter occupants from crashes, according to an Oct. 8 letter. It was spurred by a recent study showing better protections would save lives, according to the FAA letter. The agency also is asking for a review of other safety measures, including requiring seats that don’t break loose in accidents and structural changes to prevent occupants from being crushed.

New Standards

In the 1980s and 1990s, the FAA adopted helicopter safety standards for new designs. Since then, however, only 16 percent or fewer helicopters sold have the protections because manufacturers mainly produce aircraft based on older designs.

“This approach has resulted in a very low incorporation rate of occupant protection features into the rotorcraft fleet, and fatal accidents remain unacceptably high,” the FAA said.

While the helicopter industry supports reviewing whether new standards make sense, it hasn’t endorsed any specific measures, Desrosier said. Requiring fuel-tank upgrades may cost manufacturers millions of dollars, an expense that wouldn’t justify whatever benefit it creates, he said.

One option may be to create a streamlined protection system that would be cheaper to install on existing models, he said.

UT, Airbus

GAMA represents helicopter makers including United Technologies Corp.’s Sikorsky Aircraft division, Airbus Group SE’s Airbus Helicopters Inc. and Textron Inc.’s Bell Helicopter. GAMA members delivered 971 new helicopters last year, according to the group’s annual statistical report.

The Helicopter Association International, a trade group representing fleet operators, supports the FAA’s effort though it hasn’t endorsed changes to fuel tanks or other specific measures, said Chris Dancy, a spokesman. The group will work on the advisory committee, he said.

Safer fuel tanks were developed by the military in the 1960s in response to the high number of casualties in Vietnam after helicopters caught fire in the aftermath of crashes that were otherwise survivable.
Companies including Robertson Fuel Systems LLC of Tempe, Arizona, have built such tanks for military aircraft and ground vehicles, as well as race cars, according to company founder S. Harry Robertson. Their system, known as “Robbie Tanks,” work by preventing leaks even after being pierced by bullets or fractured by an impact.

The safety board on July 23 urged the FAA to impose stricter standards. The FAA agrees with the NTSB on the need to upgrade fuel tanks and has started the rulemaking process, Administrator Michael Huerta wrote in the September letter.

Wichita Crash

The NTSB’s July recommendation was prompted by an Oct. 4, 2014, helicopter accident in Wichita Falls, Texas. Surveillance video that captured the crash showed a flight nurse and paramedic survived the impact, but died when fuel spilled and ignited, according to the NTSB.

From 1994 to 2013, there were 135 helicopter accidents in which fire broke out after impact, resulting in 221 deaths and 37 serious injuries, according to NTSB. Of those crashes, only three had crash-resistant fuel systems.

After the U.S. Army began requiring fuel protections in the 1960s, it saw a 75 percent decrease in injuries and zero fatalities attributed to post-crash fires, according to the NTSB letter. The letter didn’t specify the years when the decrease took place or how many deaths there were prior to the requirement taking effect.

The FAA didn’t set a deadline for when it would complete its new regulations. It must first draft the rule and then allow the public and industry to comment.

- Source:

NTSB Identification: CEN15FA003
Nonscheduled 14 CFR Part 135: Air Taxi & Commuter
Accident occurred Saturday, October 04, 2014 in Wichita Falls, TX
Probable Cause Approval Date: 07/23/2015
Aircraft: BELL HELICOPTER TEXTRON 206L 1, registration: N335AE
Injuries: 3 Fatal, 1 Serious.

NTSB investigators either traveled in support of this investigation or conducted a significant amount of investigative work without any travel, and used data obtained from various sources to prepare this aircraft accident report.

The pilot reported that he was making an approach to a hospital helipad into light wind at night when he chose to go around because he felt that the approach was too high and fast. The pilot lowered the helicopter’s nose, added power, and raised the collective, and the helicopter then entered a rapid, “violent” right spin. A review of the last 43 seconds of the helicopter’s flight track data revealed that, as the helicopter approached the helipad, it descended from 202 to 152 ft and decelerated from a ground speed of about 9 to 5 knots before it turned right. The pilot attempted to recover from the uncommanded spin by applying left antitorque pedal and cyclic, but he was unable to recover, and the helicopter then spun several times before impacting power lines/terrain. Postaccident examination of the helicopter and the engine revealed no mechanical anomalies that would have caused the helicopter’s uncommanded right spin. The helicopter was under its maximum allowable gross weight at the time of the accident, and the wind was less than 4 knots. 

Federal Aviation Administration guidance states that the loss of tail rotor effectiveness could result in an uncommanded rapid yaw, which, if not corrected, could result in the loss of aircraft control. The guidance further indicates that, at airspeeds below translational lift, the tail rotor is required to produce nearly 100 percent of the directional control and that, if the required amount of tail rotor thrust is not available, the aircraft will yaw right. Therefore, it is likely that that the pilot did not adequately account for the helicopter’s low airspeed when he applied power to go around, which resulted in a sudden, uncommanded right yaw due to a loss of tail rotor effectiveness. 

The National Transportation Safety Board determines the probable cause(s) of this accident as follows:
The pilot’s failure to maintain yaw control when he applied power to execute a go-around at a low airspeed in dark, night conditions, which resulted in a rapid, uncommanded right yaw due to a loss of tail rotor effectiveness.

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