Crash-resistant fuel systems: determining available mods is not always easy

Avatar for Elan HeadBy Elan Head | May 17, 2016

Estimated reading time 13 minutes, 20 seconds.

A crash-resistant fuel system retrofit kit for the AS350 B3e (H125) is now available to order, although kits for older models of the AS350 will not be available until later this year. Airbus Helicopters Photo
A crash-resistant fuel system retrofit kit for the AS350 B3e (H125) is now available to order, although kits for older models of the AS350 will not be available until later this year. Airbus Helicopters Photo

The U.S. National Transportation Safety Board (NTSB) is concerned that helicopter owners and operators may find it difficult to determine whether “any modifications are available to improve fuel system crash-resistance for their particular helicopter models.”

The agency probably has a point. In fact, it appears to have had some difficulty making that determination itself.

In an April 19 safety recommendation report titled “Crash Resistant Fuel Systems on Airbus Helicopters,” the NTSB recommends that the U.S. Federal Aviation Administration (FAA) and European Aviation Safety Agency (EASA) prioritize approval of a retrofit kit to incorporate crash-resistant fuel systems (CRFS) into AS350 B3e helicopters, “once Airbus Helicopters completes development of [the] kit.”

By the time the report was published, however, Airbus Helicopters had already validated installation procedures for a CRFS retrofit kit for AS350 B3e (now called H125) helicopters. When Vertical called attention to the discrepancy, an NTSB spokesperson noted that the FAA’s supplemental type certificate (STC) database did not show any approved CRFS retrofit kits for AS350 B3 models.

But the retrofit kit coming from the manufacturer doesn’t require an STC. As an Airbus Helicopters, Inc. (AHI) spokesperson explained, the retrofit kit uses a type certificated design that was previously approved by EASA and the FAA for installation on the final assembly line. The manufacturer validated a service bulletin for the kit with respect to installation procedures, allowing the kit to be installed in aircraft previously delivered with the legacy system.

So a CRFS retrofit kit for AS350 B3e/H125 helicopters is now available to order, although it has not yet been certified to the provisions of Federal Aviation Regulations §27.952, which spells out specific design and testing requirements for fuel system crash resistance. According to the AHI spokesperson, “The H125 CRFS design is based on that of the H130, which already complies with §27.952. [Airbus Helicopters] is working with EASA on the methodology for certification to §27.952 on the H125.”

Meanwhile, Vector Aerospace is developing a CRFS retrofit solution for older AS350 series aircraft, including the EC130 B4. According to a Vector spokesperson, that solution will take the form of an STC, with FAA certification targeted for late September 2016, and EASA certification to follow shortly thereafter.

Rethinking ‘Just Don’t Crash’

The confusion over the AS350 B3e/H125 retrofit kit highlights the uneven way in which the helicopter industry is lurching toward improved occupant protection standards after decades of avoiding the issue. The FAA adopted the fuel system crash resistance standards of §27.952 and §29.952 in 1994, and the dynamic crashworthiness standards of §27/29.562 in 1989. But the standards did not apply to rotorcraft with type certificates approved before those dates, such as the AS350, which was first certified in the 1970s.

Because new variants of a rotorcraft model usually retain the original model’s type certificate, many new-production helicopters still fail to meet occupant protection standards that have now been in place for more than two decades. The helicopter industry was never unaware of this, but for many years the economic argument against retroactive application of the standards seemed overwhelming.

For this story, Airbus and Vector declined to provide cost estimates for their CRFS solutions, noting that detailed pricing information is available upon customer request. However, other sources estimated the cost of these systems at around $90,000. Confronted with this sticker shock (and, for the H125 system, a weight penalty of 41 pounds/18.5 kilograms), many helicopter operators have adopted the philosophy, “Just don’t crash.”

Unfortunately, this approach hasn’t been particularly reliable. According to the NTSB, between 1994 and 2013, at least 135 rotorcraft accidents in the U.S. — representing a total of 221 fatalities and 37 serious injuries — have resulted in a post-crash fire. Only three of those accident helicopters had crash-resistant fuel systems and crashworthy fuel tanks. An FAA analysis of fatal rotorcraft accidents over the period between 2008 and 2013 found that the post-crash fire contributed to a fatality in 20 percent of accidents where one was present.

Despite the frequency of post-crash fires, the argument for wider adoption of crash-resistant fuel systems didn’t gain much traction until one particularly high-profile accident last summer. On July 3, 2015, a Flight For Life H125 operated by Air Methods crashed shortly after takeoff from Summit Medical Center in Frisco, Colorado. The impact and ensuing fire were captured on surveillance video, and images from the fiery crash were widely circulated in news reports.

According to the NTSB, all three occupants — including pilot Patrick Mahany, and flight nurses Dave Repsher and Matthew Bowe — survived the initial impact. Bowe sustained a back injury and Repsher sustained serious thermal injuries, and a medical staff member on the ground also sustained thermal injuries while trying to rescue Mahany from the wreckage. Mahany ultimately died from his injuries, while Repsher remained hospitalized nine months after the accident.

The Flight For Life accident may have been the second Air Methods crash last year in which a post-crash fire contributed to a fatality or serious injury. In its recent safety recommendation report, the NTSB claims that pilot Ronald Rector survived the initial crash of his ARCH Air Medical EC130 B4 in St. Louis, Missouri, on March 6, but died from subsequent thermal injuries. Neither the Flight for Life H125 nor the ARCH EC130 B4 was equipped with a CRFS.

The negative media attention associated with the Flight For Life crash made the industry especially receptive to a safety recommendation issued by the NTSB on July 23, 2015, which called for all new-build helicopters to meet the fuel system crash resistance requirements of §27.952 or §29.952. By November, the FAA had announced the creation of an Aviation Rulemaking Advisory Committee Rotorcraft Protection Occupant Working Group, whose first task was to perform a cost-benefit analysis for incorporating existing occupant protection standards into newly manufactured rotorcraft.

Meanwhile, also in November, the Air Medical Operators Association committed to the installation of CRFS in all new aircraft, and equipping current aircraft with CRFS as those products become available. A few months later, the Commission on Accreditation of Medical Transport Systems (CAMTS) announced that the 11th edition of the CAMTS Standards will encourage all helicopters to have a CRFS that meets the standards of §27.952 or §29.952.

Other sectors of the industry haven’t felt the same intense pressure to jump on the CRFS bandwagon, but are starting to pay attention. When contacted by Vertical, a U.S. Forest Service spokesperson said that although the agency at this time is not requiring fuel system crash resistance improvements for its contracted aircraft, its Technical Evaluation Board has previously chosen not to penalize the weight gain associated with certain safety improvements, and may give similar consideration to CRFS.

All of Bell's production helicopters, including the Bell 407, are equipped with CRFS. However, some older Bell aircraft are still flying without CRFS, despite the availability of retrofit kits. Skip Robinson Photo
All of Bell’s production helicopters, including the Bell 407, are equipped with CRFS. However, some older Bell aircraft are still flying without CRFS, despite the availability of retrofit kits. Skip Robinson Photo
A CRFS is standard equipment on the Airbus Helicopters H130 (formerly known as the EC130 T2), which is the newest version of the EC130. For the past year, Airbus has also made a CRFS standard on all H125 helicopters built in the U.S., although customers who wish to avoid the expense can order an H125 without a CRFS from the main production line in Marignane, France.Other helicopter manufacturers have adopted fuel system crash-resistance improvements at different times. Following a series of post-crash fires in R44 helicopters, Robinson Helicopter Company began installing bladder-type fuel tanks on all new-build R44s in 2009, and in 2010 issued a service bulletin calling for older R44s to have their fuel systems retrofitted. (Australia’s Civil Aviation Safety Authority made that retrofit mandatory, but the FAA declined to follow suit.) The R66 Turbine has a CRFS as standard equipment, and R22s are also now built with bladder-type fuel tanks.

Bell Helicopter was an early adopter of CRFS, having converted all of its existing production helicopters to CRFS by 1991. Among its current production aircraft, the fuel systems on the Bell 407 and 429 are certified to 27/29.952 standards, while the systems on the 206L4 and 412 incorporate crash-resistant features without having demonstrated 27/29.952 compliance, as they were developed prior to the rules existing.

“The Bell CRFS systems were designed by Bell using a modified version of the military CRFS standard,” a Bell spokesperson explained. “The FAA largely adopted the Bell standard when drafting their regulation. So while Bell models with type-certificates pre-dating 1994 are not formally certified to the current FAA standard — since it didn’t exist at the time — the Bell CRFS meets the safety intent adopted by the FAA with its regulation.”

Bell has offered retrofit kits for most of its models produced without CRFS since 1994 (with CRFS retrofit kits currently available for the Bell 212, 206A, 206B, 206L, and 206L1). Despite this fact, many older Bell helicopters are currently flying without CRFS. In the safety recommendation it issued last year, the NTSB called attention to the fatal crash of a Bell 206L1+ air medical helicopter in October 2014, in which thermal injuries contributed to the death of the flight nurse and paramedic. According to the NTSB, that aircraft was manufactured in 1981, and did not have a CRFS.

More recently, news reports have indicated that four of the five victims of a sightseeing helicopter crash in Pigeon Forge, Tennessee, last month died as a result of the post-crash fire. According to the FAA Registry, that aircraft — a Bell 206L — was manufactured in 1977.

As the NTSB points out in its most recent safety recommendation report, several factors can make it difficult for operators to learn about available retrofits for improving their fuel systems’ crashworthiness. Owners and operators may not be notified about modifications produced by third-party manufacturers, and the search function for the FAA’s database of STCs “is not easy to use unless users know what they are looking for,” the report states.

“Adding to the difficulty,” the report continues, “a modification could be announced via a service bulletin, which would not be included in the STC database.”

For these reasons, the NTSB is recommending that the FAA issue “a special airworthiness information bulletin [SAIB] that is periodically updated to inform all helicopter owners and operators about available modifications to improve fuel system crashworthiness and urge that they be installed as soon as practicable.”

In an email to Vertical, an FAA spokesperson declined to indicate whether the FAA plans to issue such a bulletin, instead calling attention to the creation of the Rotorcraft Occupant Protection Working Group. “The agency will review the group’s work and take whatever action is necessary to improve safety,” the spokesperson stated.

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