Wednesday, July 1, 2009
Racecars with Wings: Maintenance on the Red Bull Circuit
Maintenance is part of every aircraft’s lifespan, from an annual on a GA aircraft to a heavy D-check on an Airbus or Boeing commercial jet. Schedules are typically defined as regular interval checkups or unplanned events. But in the Red Bull air-racing universe, unique aircraft maintenance and modification practices are not only critical to safety — with fast speeds, operating in close proximity to the ground and pulling high g-loads — they are the lifeblood of the burgeoning sport.
Michael Goulian, one of the Red Bull Air Race (RBAR) pilots, flies a Zivko Aeronautics Edge 540 with a modified Lycoming Thunderbolt AEIO-540-D4A5. The designations stand for aerobatic (AE), fuel injected (I) and horizontally opposed (O). For air shows, he flies an Extra 330SC with a 350-hp Thunderbolt AEIO-580-B1A.
Time-lapse photo of Red Bull Air Race pilot Mike Goulian flying through a gate during the 2008 race in San Diego, Calif. Photo by Mike Shore.
Goulian explains that each Red Bull team is comprised of three people — a pilot, chief technician and team coordinator. For his team, the chief technician is Timothy Hess. While the coordinator, Brad Huelsman, is charged with day-to-day operations in managing the unit, the mechanic/technician/engineer "is pretty much 100 percent solely responsible for the maintenance and the condition of the plane," Goulian says.
Zivko Edge 540
Guthrie, Okla.-based Zivko Aeronautics Inc. (ZAI) makes the Edge 540, the aircraft that 10 of the 15 Red Bull pilots use, including Hannes Arch, Paul Bonhomme, Kirby Chambliss, Nicolas Ivanoff, Mike Mangold, Pete McLeod and Yoshihide Muroya. The other five fly the MXS-R from MX Aircraft of Wilkesboro, N.C. Lycoming, LyCon Aircraft Engines, Visalia, Calif., and Tulsa-based Barrett Precision Engines are the approved powerplant options for the Red Bull Air Race.
According to Eric Zivko, vice president of operations, ZAI got involved with Red Bull though Arch, who initially purchased an Edge 540T (two-seat) in 2002 before getting a single-place E-540. Arch has been involved with the energy drink company since the inception of the races, and the E-540 proved to be a winner early on in the series, which led more pilots to fly it, Zivko explains. ZAI does provide some materials to help with repairs, such as parts specially made for composites that are harder to obtain, according to Zivko. Examples include a "Clip Bond" or bond-on nut plate, resins and carbon fiber material. ZAI also provides hardware assistance for some of the teams.
Short Maintenance Cycle
"Essentially, these airplanes are undergoing maintenance every day all day," Goulian says. They don’t undergo scheduled checkups "because they’re always under maintenance. We are changing the timing of the magnetos during the races, depending on the temps. We’re looking at the fuel stream every race, we’re looking at the brakes every race," he explains.
"It’s just a very different way of operating, an operating philosophy. For our airplanes, maintenance comes first. For us, maintenance is performance. It’s not a necessary evil, it’s something we want to do."
Speed & Weight
The whole idea behind the Red Bull event is speed, Goulian says, "but in addition to speed it’s acceleration. We need the airplane to be able to accelerate as quickly as possible."
According to RBAR rules, the minimum weight of the aircraft is around 1,190 lbs. A typical factory version of the Zivko Edge 540 is around 1,240 lbs.
"To get to 1,190, basically you have to somehow try to figure out how to get 50 pounds out of the plane, which for an airplane that’s already been designed to be lightweight, isn’t an easy task," Goulian notes.
As far as avionics, a Red Bull aircraft has "nothing in them. It’s just a radio and a transponder, everybody has a portable GPS that they put in just to fly the airplanes around, but that’s it," he continues.
"We’ve even gone to the point where we get manifold pressure, fuel flow, RPMs and everything from a [JP Instruments] EDM800 as opposed to a mechanical gauge, because having the direct reading gauges is heavy, so we get all of our information from the one little EDM800, just to save weight."
The structure of the airframe is not allowed to change under RBAR rules. However, Goulian notes, "all of the fairings, belly panels, canopies and everything else are just paper-thin carbon fiber, to try to save weight." That results in "an unbelievable amount of wear just from race to race or from flight to flight, where you see things cracking and splitting. Basically the parts on our airplanes have a shelf life of about a season," he says.
For instance, Goulian’s Edge 540 has a modified carbon fiber belly panel that weighs around five pounds, as opposed to the production-version panel weight of 19 lbs.
"But we’re only expecting it to last 75 hours, as opposed to 1,000, 1,500 or 2,000 hours on the original one that came out of the factory mold," Goulian says. The same applies to the wheel pans. "You can almost twist them with your hand and break them in half." Another modification is a specially designed tail wheel that is four pounds lighter than its factory counterpart. But again, the component "doesn’t really have any durability whatsoever," so they are just put on for qualifying and race day events.
"This is definitely a racecar with wings," Goulian says. "It’s really meant flight per flight and the maintenance elements change every time from an airframe standpoint," he continues, adding that the modifications do not decease the safety and reliability of the aircraft, because the main airframe structure remains the same.
Just like with the airframe, a similar short life cycle applies to the engines. They are looked at from a parameter standpoint after every flight, and the oil and filter are changed every six hours, or following each race.
"Every time the plane lands, my engineer goes over to the EDM800, downloads all the info and looks at every little detail of the flight," Goulian says, including an oil analysis and examination of fuel flow fluctuations, cylinder head temperatures, RPMs, manifold pressure and whether the engine is leaning too much.
Jeff Schans is Thunderbolt manager for Lycoming, which sponsors Goulian and Kirby Chambliss. Schans started out in the military before getting his A&P and IA. He then worked as a maintenance manager at a small fixed-base operation before becoming a tech rep at Lycoming, which has headquarters in Williamsport, Pa. He says that the weight difference between the connecting rods and pistons in the Thunderbolt is down to a half a gram.
Engines are "the difference between winning and losing in an Red Bull Air Race right now because it’s all a horsepower to weight gain equation," Goulian says, "and we’re not expecting the engine to serve us more than 100 hours." After about 75 hours the engines will be completely disassembled and examined, and parts that exhibit wear and tear will be replaced. For example, the magnetos are switched out annually. "We’re asking a lot from this engine and from the components. When the season’s over, we will throw them away and get new ones only because we know that we’ve overheated them a lot," he adds.
Lycoming sponsors Goulian for both the Zivko Edge 540 in the Red Bull Air Race and his Extra 330-SC for air show performances. Shown here is the Thunderbolt AEIO-540-D4A5 on the Edge 540.
The engines feature a 10-to-1 compression ratio for the pistons. Modifications performed by the RBAR teams include port and polishing the cylinders, which are volumetrically balanced between each other, according to Schans. Goulian, who notes that teams are also changing the cam shaft profiles and modifying the intake systems to breathe more air, says Red Bull doesn’t allow more than a 10-to-1 ratio for safety and reliability reasons from flying near cities and over water. Air show performers have been known to push the ratio to 11 or 11.5-to-1.
Schans points out that the Thunderbolt 10-to-1 pistons "were subjected to an FAA type test, a 150-hour endurance test in a turbocharged engine. So it was more severe service than the engine would normally see, and it ran about 230 hours of testing."
Engine parts are available on quick notice. "We travel with a spare cylinder, spark plugs and magnetos, and a spare set of harnesses, and things like that for the engine, but [if we break] something that’s more exotic or something that we didn’t plan on breaking, then we can get a part anywhere we need, especially in the U.S. same day, and overnight around the globe," Goulian says. If by remote chance there was a full engine failure, RBAR carries a brand new Lycoming as a backup for race day.
According to Goulian, the Red Bull Air Race started with a group of around 10 pilots that had an excessive amount of air show experience and background in aerobatic racing. "One of the requirements was you had to either be a national champion or a world champion in your own country," he says. "Everybody was a bunch of aerobatic, sort of ‘superstars’ that really wanted to live more than they wanted to win." Due to the low and high-speed flying, "they wanted people that were comfortable in that environment. When they were trying to get the series really started, the last thing anybody ever needed was an accident."
Goulian recalls a course in Hungary a few years back that involved flying under a bridge. When the event went to Portugal, organizers asked for a similar aerobatic maneuver under a bridge, "which was the same height off the water, but the visuals were completely different — it was painted gray, steel and not cement, on a huge river [with] no landmarks around it, we were flying into the sun, and you couldn’t really see it. And the pilots said, ‘No, we’re to going to do this.’"
As a result, overnight crews "actually turned the racetrack around 180 degrees so we didn’t fly under the bridge," he adds.
Whether it involves a Red Bull event, air show performers, the Blue Angels, or even with the car racing industry, "you have to have a relationship and a trust that’s built into the crew chief that you don’t have in any other type of motor sport," Goulian says. "Because if we have an engine failure, an airframe failure, or if there is an accident for some reason, the consequences are a lot more dire than they are in a racecar."
The bond that’s built between the pilot and the engineer is critical.
"For me to go out and to fly a Red Bull Air Race as well as I can, the machine and its reliability never even enter my mind," he says.
Left to right, Timothy Hess, chief technician, pilot Mike Goulian and team coordinator Brad Huelsman in the Red Bull Air Race hangar at Abu Dhabi in the lead-up to the April 2009 event.
"I don’t think about whether the modifications we did to the airframe are ever going to work, and we’re always pushing to get closer and closer to the edge." Hess knows that Goulian has a family at home and is constantly looking out for his safety.
"It’s really the technician and the pilot’s bond that makes it safe. And you have to have trust in that person, because otherwise, you’ll never fly with the full freedom to go out and do it as hard as you can." Goulian’s pre-flight checklist is just basically a cursory once-over on the aircraft to check fuel and oil, make sure the onboard camera is turned on, and the water bottle is full. He leaves the worrying about mechanical issues to Hess. "I look at him and he looks at me, and I say ‘is it ready to go?’ He says yes, and I trust him and get in and go." Mechanics in the air race are passionate about their jobs. "Tim is one of those people, he has an engineering background and engineering mind, and is always thinking about ways to do it better. Not only is he reading about aviation maintenance, but also Formula One-style, NASCAR, or engineering magazines," Goulian notes. A pilot, Hess has an A&P and IA and in a previous job spent some time building specialty race engines for the automobile industry. "He’s always thinking 24/7 about how to make the team faster and safer at the same time," Goulian says. "That’s the kind of person you’ll find in the air races. They have a varied background, and most of the techs are pilots as well."
Birds & Pylons
Hannes Arch hit a bird during a May 9 race in San Diego, breaking the front spar and forcing the aircraft to return to ZAI for repairs.
If you ask any of the pilots, Goulian says, the biggest challenge to Red Bull racers is hitting the pylons that are set up along the course. He has grazed a couple of pylons during his career, once in Abu Dhabi in 2006 and last year in London.
In terms of bird strikes, Goulian says that the incident with Arch was unusual. While birds may try to congregate on the barges that support the pylons, a helicopter that takes high-definition images of the races is also used to scare away wildlife. "We’ve really never had a bird strike like the one at the San Diego race, until this last time," he points out.
Austria’s Hannes Arch struck a bird during the May 2009 Red Bull Air Race in San Diego, as shown in the two images above. After finishing the race, the aircraft was transferred back to the manufacturer, Zivko Aeronautics, which installed a new tail in time for the next race, held in Windsor, Canada June 13–14. Lower two images show before and after of the repair work at ZAI. Despite the setback, Arch leads the overall standings by one point (33) over Great Britain’s Paul Bonhomme (32) through mid-June.
Zivko says that they see damage that requires a return to the manufacturer about once a year, on average. This year it is Arch’s bird strike, and last year it was Steve Jones hitting a pylon. Small bird strikes, such as on the leading edge of the wing or under it, or on the wheel pants, can be repaired by individual team mechanics. "That’s one nice thing about composites. It’s fairly easy to fix damage in the field, as long as it doesn’t effect the structure itself," Zivko says. One of the advantages to the ZAI wing design is its outside skin, half-inch core and inside skin.
"Typically, most of the damage is on the outside skin and then it just gets into the foam core, so you don’t totally destroy the structure. You can repair just the outside plies," he continues. Goulian adds that RBAR has done an "unbelievable" amount of research on pylon impact scenarios using live aircraft and simulations.
"They’ve actually taken wings and mounted them to the top of a pickup truck, driving 110 mph and at all different levels, and hitting the pylon, and things like that," he says, adding that the manufacturers have also studied the impacts. "It really doesn’t do any damage to the airplane."
Turnaround time for a repair on a Red Bull Edge 540 is pretty quick, within a week, according to Zivko. Larger repairs can take a few weeks to a couple months.
With the Arch bird strike, "we just happened to have one already in construction," he says, which allowed installation of a new tail in a week and a half. "Usually the tail is a month-and-a-half project. If we did not have this one part in house, he probably wouldn’t be attending this next race [in Windsor, Canada]."
"We just did one of Red Bull’s airplanes a couple months ago," Zivko adds. "It came back here and we totally stripped it to the bare fuselage. It was bead blasted, pressure checked, inspected and repainted, and all the steel parts had this done. The airplane was basically rebuilt."
Zivko explains that FAA does not issue airworthiness directives (ADs) for experimental aircraft, except for some parts, but rather E-540 corrections are handled through service bulletins (SBs) from ZAI. While experimental aircraft manufacturers are not required to provide them, ZAI will send out SBs "if something happens to one of the airplanes. If it’s just a single incident, depending on what it is, we’ll send out a bulletin to all the owners," he says, adding that even with all the abuse and wear the aircraft take in the Red Bull races, the Edge 540 has not had an SB in the past four or five years.
Schans echoes the sentiment in terms of the engines: "With the Thunderbolt, it’s all experimental, so there really is no certification paperwork that’s needed, but the good thing is that the parts that are available are pretty much all certified, except for the special things that we do to the engine, basically."
Rick Karaschin, manager of Lycoming’s Advanced Technology Center, explains that "all of the parts that come into the Lycoming plant go through the same quality and receiving inspections, and all of the things that are required for a typical engine program, to meet our FAA requirement to build certified engines."
"The base parts used to construct a Thunderbolt — crankcase, crankshaft, all those major parts — they all come from the same source," he continues, "so they’re essentially certified parts." But Karaschin says once modifications take place beyond the base parts, for instance if the pistons were not certified, "they were still tested to the FAA type certificate, to make sure they’re still a durable part. Those parts may not be certified, but as an experimental engine, they’re not required to be."
Zivko says it’s important to remember that everything about the Red Bull Air Race is highly regulated. "Even though if you attend a race and it looks very dangerous, it isn’t. The airplanes are very well taken care of — it’s not a free-for-all that these crazy guys are going out there and trying to kill themselves."
Upcoming 2009 Red Bull Air Races
August 19: Budapest, Hungary
September 12: Porto, Portugal
October 3: Barcelona, Spain