Posted 20 days ago ago by jhadmin
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In the world of rotorcraft emergencies, not all situations are equal. There’s a huge difference between a generator failure, engine fire or anti-torque system failure. I think if you were to poll pilots, just the mention of certain crises will make the hair stand up on the back of every pilot’s neck, and they pray that it never will happen to them. For me, there are two such crises: a tail-rotor gearbox failure, and any situation that would cause me to hit the ground hard enough to rupture a fuel tank and spark a post-crash fire.
What could be worse than wrestling a helicopter to a hard landing following an emergency, only to have the fuel tank(s) rupture and catch on fire?
That’s exactly what occurred in a fiery high-profile case in July 2015, when an air ambulance pilot was killed in a crash of a Flight for Life AS350 helicopter in Frisco, Colorado, following the loss of hydraulic pressure on takeoff. The crash seriously injured one flight nurse and severely disfigured the other with life threatening burns.
Fortunately for us pilots, passengers, and crews, more modern helicopter fuel systems are being designed to have crash-resistant features built into them, and there’s little doubt they can drastically reduce the chance of a post-crash fire. However, many legacy aircraft are still operating without this crucial protection.
Although the military established crashworthy military specification helicopter standards nearly a half-century ago, its civilian counterparts have lagged behind. It was not until 1994 that the FAA established 14 CFR 27/29.952 to require Crash-Resistant Fuel Systems (CRFS) for all newly certified civil helicopters.
But don’t be confused by the terminology. There’s a big difference between the date of certification of the Type Certificate (TC) and the date of manufacture. Take the AS350 from the Frisco accident, which was manufactured in 2013, as an example. The popular Eurocopter AS350 airframe, also known as the Airbus H125 since the company changed names in 2014, was TC’d in 1977. Thousands of aircraft with several variants were developed and manufactured under that TC including the EC130 B4, AS350 B3, B2, BA, B1, B and D models. Some were manufactured before the 1994 regulatory change, but many were also manufactured after 1994, and the way the regulation was written, those made after 1994 did not require CRFT installation.
All Airbus aircraft typed after 1994 have CRFSs. For example, CRFS has been standard on the H130 (EC130 T2) since the aircraft’s entry into service in 2012. The company currently offers its own retrofit kit for the H125 (AS350 B3e) and is in the development phase for kits for the AS350 B3 and EC130 B4. Any Airbus H125 or H130 family helicopter in service today that does not have a CRFS can be equipped with one through either an Airbus or third party retrofit solution, based on the model.
Additionally, Airbus’ ongoing testing includes CRFSs for the H125, AS350 B3, and EC130 which will certify the CRFS to the more stringent FAR 27/29.952 requirements to include testing with the underbelly cargo swing configuration.
ACCIDENT DRIVES SAFETY INITIATIVES
It was the 2015 Frisco accident that brought this CRFS issue to a fever pitch in the regulatory community. It spawned several initiatives to convince the FAA to require CRFSs to be retrofitted into legacy aircraft.
A grassroots safety group called “Save Our Crews” was created by the wife of the deceased Flight for Life pilot in 2015. Earlier this year the group worked with several U.S. senators and representatives from Colorado to reintroduce the Safe Helicopters Now Act, H.R. 675. It would offer a 10-percent tax credit to helicopter operators who retrofit their air ambulance helicopter fleets with CRFSs.
In 2018 the FAA Rotorcraft Occupant Protection Working Group (ROPWG) – also formed in 2015 after the Flight for Life accident – made several safety recommendations. They included upper-torso restraints for passengers and CRFT retrofits on all helicopters within three to five years, including those type certified before 1994. At the same time, the NTSB was making similar recommendations.
The 2018 FAA Reauthorization Act mandated CRFTs for all helicopters manufactured after April 5, 2020 (regardless of type certificate, closing the door on grandfathering). The new legislation required OEMs to comply with most, but not all, of the requirements in (FAR) 27/29.952, which mandates CRFT standards for civil helicopters certified after 1994. The differences between the 2018 Reauthorization Act and the original 27/29.952 requirements from 1994 are a compromise designed to make it easier and faster for OEMs to certify CRFTs for the thousands of legacy model aircraft currently flying around the world.
PRIOR EXPERIENCE PROVES USEFUL
Robertson Fuel Systems, based in Tempe, Arizona and founded by safety research engineer Dr. S. Harry Robertson in 1976, is known for its rugged Robbie Tank fuel bladders that were designed as auxiliary fuel systems and range extenders for military aircraft operating in a variety of extreme conditions including combat.
As a military pilot, Dr. Robertson observed trends in fatal aircraft crashes that would have been survivable without their post-crash fires. He made it his personal mission to research and develop military aircraft fuel tanks and extension systems that would not only be crashworthy, but also ballistically self-sealing. Over the decades, Robertson developed Crashworthy Primary and Auxiliary Fuel Systems for most military helicopters flying today. He established the Robertson Safety Center at Embry-Riddle Aeronautical University in Prescott, Arizona to ensure a permanent home for his pioneering safety designs. He was inducted into the National Aviation Hall of Fame in 2011.
In the mid ‘90s, Robertson Fuel Systems worked with Eurocopter (now Airbus), which was competing for a U.S. Army new training helicopter, to develop a CRFS for the AS350. Eurocopter did not get the contract and the product was shelved.
Fast-forward 20 years when StandardAero and Robertson, while working on a separate program for the Super Puma, decided to expand Robertson’s proven fuel retention technology into the civil helicopter space, recognizing the AS350 platform as a viable market and the opportunity to leverage StandardAero’s deep structural experience and knowledge of the airframe. Together, they pulled the product back off the shelf, dusted it off, and set out to develop, test and certify a CRFS for the airframe, now known as the Crash-Resistant Fuel Tank (CRFT).
ROBERTSON TEAMS UP WITH STANDARDAERO
Developing a safe and economically viable CRFS system for the AS350 was challenging, but still only half the equation. As with most things in civil aviation development, getting the product built is one thing; getting it certified by the FAA, EASA, and other global airworthiness authorities is another animal completely.
To bring the product to market, Robertson teamed up with StandardAero to navigate the complicated and lengthy process of obtaining an STC for the AS350 CRFT. “StandardAero had worked with Robertson on other projects and during the course of that experience, it sort of became a natural fit to work together on developing and certifying the complex CRFT STC for the AS350,” reflected Elvis Moniz, StandardAero VP of Business Development for Airframe and Avionics Solutions.
LEGACY SOLUTION OVERCOMES CHALLENGE
Robertson has the capability to perform virtually every type of test including drop tests, slosh tests, vibration tests, and even ballistic testing, since it has military tanks that can reseal themselves after being shot by a .50 caliber round. But there are differences for an FAA certification, including an additional parameter into the drop testing process.
It was challenging enough to develop a CRFT that could withstand the normal 50-foot drop test with tanks 80% full of water. But the AS350 had a cargo swing mounted underneath the helicopter that is commonly used for firefighting and sling load operations. So the new challenge was to drop an AS350 airframe with a cargo swing, without skids, at 80% full of water from 50 feet and prevent the cargo swing from penetrating the fuel tank, or prevent a rupture of any kind.
StandardAero and Robertson Fuel Systems met the challenge. In late 2017 they announced that they were the first to develop, test, and successfully certify their CRFT for virtually all models of the AS350 with a cargo swing to the standards of 27/29.952, including virtually all legacy aircraft.
“Including the cargo swing in the drop test was a good thing, as it caused us to develop a lot of robustness in the tank which makes it safer in real-world environments where object penetration is more likely in a hard landing,” concluded Bill York, director of engineering for Robertson.
DESIGN ELEMENTS OF THE STANDARDAERO / ROBERTSON CRFT
- Self-sealing breakaway valve to prevent fuel leakage
- Vent system rollover protection
- Vent system flame arrestor
- Crash-resistant recessed sump drain valve
- Compatible with Onboard Systems’ industry-proven cargo swing solutions, as well as the Airbus Helicopters cargo swing
- Quick-change cartridge-style boost pump, replaceable without draining fuel
- Independent low fuel level sensor
- Single or dual pump configurations
- Compatible with aftermarket fuel filter
- Composite container specially engineered to distribute impact loads
- Compatible with popular cargo pods
- Compatible with virtually all models via AML STC
CRFT RETROFIT BARRIERS
Unfortunately, barriers to CRFS retrofits remain.
“One of the largest barriers I see in the civil market is a lack of familiarity with CRFT, as well as understanding the risks of not having it,” said Carl Hessberger, director of customer service for StandardAero.
Many operators view CRFTs as just another piece of insurance, observed Manny Atwal, VP of sales, marketing and business development for StandardAero commercial helicopter programs. In other words, they may focus on the operational needs of today and tomorrow while viewing CRFTs as something needed only when something catastrophic happens. “For us, the challenge is to make sure that people are aware that not only is there significant risk that is real, but the risk can be mitigated,” Atwal said. Awareness is on the rise, it seems; to date, approximately 160 StandardAero/Robertson CRFT systems have been installed on AS350 airframes.
Cost may also be a part of the decision-making process. The StandardAero/Robertson AS350 CRFT costs approximately $100,000. To help indirectly offset some of the cost, Airbus offers operators who use a third -party retrofit solution, up to $25k, per aircraft installation, in training credits at the factory training center to reduce costs associated with initial or annual training. One could also pose the question, what are the costs of not having CRFT if a preventable post-crash fire occurs? If past precedent in the Frisco crash is any indication, they could exceed $100 million.
Currently there are regulatory barriers as well. “Although there’s a requirement for all aircraft typed and manufactured after 1994, there’s only strong recommendations from regulatory agencies to retrofit the remaining aircraft, and for the time being, operators may lean on that to avoid CRFT installation,” Hessberger said.
DISPELLING COMMON CRFT MISCONCEPTIONS
One of the most common misconceptions is that the lead time to receive a CRFT from StandardAero is a year or more, Hessberger said. There were some lead time constraints in the early rollout phases as Robertson was ramping up the production line. But today, operators can expect to receive their CRFTs within 60 to 90 days, if not sooner.
Another misconception is that the operator will incur a large weight penalty. Although the addition of the CRFT will increase the empty weight of the aircraft by 48 pounds, some of the most weight-sensitive operators such as air ambulances have been able to adjust. As an example, Air Methods, the world’s largest air ambulance operator, has been one of the most proactive customers. It has retrofitted most of its fleet with the StandardAero/Robertson CRFT.
“I am pleased to say, we have been very impressed overall with the end product that StandardAero and Robertson were able to deliver, which has significantly improved the safety of our crews and passengers, giving them confidence in the solution we chose,” said Leo Morrissette, EVP of operations for Air Methods. “The engineered durability of the tank, in combination with a number of ease-of-maintenance and airframe and equipment compatibility considerations that they built into the design, have brought an exceptional level of quality and safety to the aircraft.”
Bill York, Robertson’s director of engineering, said the helicopter industry needs a culture change that starts with education. “If you tell someone born after 2000 that cars didn’t used to have seat belts, they would think you are crazy,” York said. “So there has to be a cultural shift in what the pilots, regulators, operators, and insurers expect from a safety equipment standpoint, and that will take time.”
York hopes that through awareness, the culture will change and CRFSs will become as common in the future as seatbelts in cars are today.
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