Several European helicopter pilots recently formed the Flying Bulls, the only civil helicopter aerobatic team in Europe. The team uses the BO 105 for its performances, the most recent of which took place in Kitzbuhel, Austria, on January 27.
Licensed aerobatic helicopter pilots are a tiny fraternity in Europe. Pilot Rainer Wilke, a former German military pilot and the Flying Bulls’ only licensed helicopter pilot so far, is now training two more pilots–one for the U.S. Red Bull team and one in Europe for the Flying Bulls. He conducts most of the training in the U.S., where the weather is better. “We fly helicopter aerobatics under experimental rules, which impose fewer restrictions,” Wilke told AIN. Separately, there are two other licensed aerobatic helicopter pilots in Europe (a former and current Eurocopter test pilot), but they do not fly for the Flying Bulls.
Wilke said the group chose the BO 105 because it is the only helicopter authorized for such operations. “Normally, you need a legally aerobatic-licensed helicopter, but none exist,” he said. The only solution is therefore to get a special authorization from the manufacturer, which is what the team did. The Flying Bulls petitioned Eurocopter for permission to use the twin turbine for aerobatics, and the company gave its blessing.
“MBB [which later merged into Eurocopter] engineers had aerobatics in mind when they designed the BO 105 in the 1970s,” Wilke said. As a result, it can perform some of the same maneuvers–rolls and loops, for example–as a fixed-wing aircraft.
A feature of the BO 105 is its rigid (hingeless) rotor. “As an early rigid-rotor design, it has a huge safety margin built in,” Wilke said. Perhaps the most important safety benefit is that it is impossible for the rotor to touch the tailboom.
Limitations are minus 0.5g and plus 3.1g in negative and positive accelerations, respectively. Frequent airframe checks are required. “The helicopter has to undergo a maintenance check every 10 hours of actual aerobatic flight,” Wilke told AIN. This translates into some 80 flight hours. In civil applications, the BO 105 has no life limit, but that might change for those used in aerobatic applications. The first 10-hour check will help determine whether the aerobatic types will have a life limit.
The Flying Bulls have two BO 105s in Europe, while the Red Bull airborne team has two in the U.S.