High-impact windscreens give pilots better protection in mitigating bird strikes.
Over the past few years, the number of reported aircraft bird strikes has increased notably, according to the FAA Wildlife Strike Database. Even when we use long-known bird-strike mitigation strategies such as reducing airspeed, flying higher, and using specialized lighting, our avian friends continue to defy our best efforts.
Thankfully, most of these impacts involve small birds and are minor, resulting in no or minimal damage to the aircraft; impacts with large species, however, have the potential to disable the pilot, crew, and the helicopter itself. This possibility effectively leaves our last line of defense, the thin plastic windscreen—which adeptly keeps us sheltered from the elements (and bugs out of our teeth)—vulnerable to penetration.
It may come as a surprise to many readers that the only US regulations pertaining to impact tolerances for bird strikes in rotorcraft are found in 14 CFR Part 29, which covers transport helicopters, and include both the windscreen and critical flight structures. For normal category rotorcraft, specifically Part 27 helicopters, such regulations are impractical due to structure, performance, and center of gravity concerns. However, the existing Part 29 regulations provide a good target for two industry-leading aircraft manufacturers who’ve taken it upon themselves to provide safe, high-impact windscreen (HIW) options for customers.
I recently corresponded via email with Kurt Robinson, president and chairman of Robinson Helicopter Co., and Bill Sumner, senior manager of engineering at Bell Helicopter, about their HIW products and their companies’ efforts to increase rotorcraft safety.
Why did you invest in research and development of high-impact windscreens even though it’s not required?
Kurt Robinson: Robinson continuously reviews the accident reports on our helicopters, particularly those involving fatalities or serious injury. We noted the number of accidents involving bird strikes and wanted to see if there was anything we could do to minimize or reduce these types of accidents.
Bill Sumner: Bell developed the first crash-resistant fuel cells for commercial helicopters in the late ’70s, and we implemented that safety feature across our entire production line 15 years before the FAA developed a regulation requiring it. We’ve worked on impact-resistant windscreens for years.
With no basic standards in place, how did you decide what degree of protection to adopt, and roughly how long was your development process from product conception to completion?
Robinson: We looked to Part 29 and wanted to get as close as we could to meeting those requirements. Although we’ve thought about this issue for many years, once we came up with a concept we thought would work, it took us about four years to get the windows developed and approved.
Sumner: For our tests, we use the Part 29 requirements for impact from a 2.2 lb. bird at VNE [never-exceed speed]. Birds vary in size and speed, but this test has been used as the “standard” for many years. We know it provides protection in real life.
How did you overcome weight and center of gravity (CG) issues?
Robinson: Weight and CG are always part of [our] design criteria. We’re proud of the fact that, at 1.0 to 1.3 lb., the high-impact windshields are only slightly heavier than the standard windshields.
Sumner: Weight and CG were both very significant issues, as it’s essential to have sufficient structure to retain the windscreen during an impact event.
Bell’s work on impact-resistant windscreens goes back many years, and based on that experience, we developed a patented approach to the windscreen-retention issue that reduces the need for additional structure.
Is your HIW for new helicopters only, or can it be retrofitted onto older ones as well?
Robinson: At the moment, our windows are available on new aircraft and aircraft returned to the factory for overhaul. Due to the structural cabin requirements, we don’t offer a field kit.
Sumner: All our designs can be retrofitted to older aircraft. They’re designed and certified as replacement windshields.
How have HIWs been received by your customers?
Robinson: The optional high-impact windows have been very popular, particularly for those operating in regions where birds are a factor.
Sumner: They’re very popular and becoming more so. The additional cost varies between types, but it’s significant. … It’s worth it.
Do you offer high-impact windscreens on any of your current models or plan to offer them on any models in the near future?
Robinson: HIW is offered as an option on all our models.
Sumner: We currently offer impact-resistant windscreens on the Bell 206, 407, 412, and 429. We plan to offer them on other models as well, perhaps including other manufacturers’ models.
Come Home Safety after Every Flight
Developing or purchasing high-impact windscreens, just as for any other occupant-protection equipment, can be an expensive endeavor. Yet operators hopefully can quickly offset such costs by reducing the severity of—or preventing—tragic crashes and expensive repairs.
HIWs may also help reduce operator insurance premiums, so if you’re considering purchasing them, a quick discussion with a broker may help guide you in the decision-making process.
Opting for HIWs might not be the right financial choice for everyone. But remember, birds can appear anywhere at any time, especially for those flying in known problem areas or on high at-risk missions such as air ambulance flights.
Even when we make the most diligent plans and follow established mitigation techniques to the highest possible level, birds—and quite possibly drones—may still find their way into our personal space (helmets on and visors down at all times!). Selecting a high-impact windscreen and other occupant-protection equipment will give pilots, crews, and passengers that last line of defense that allows us to come home safely after every flight.