Engine accessories: starters, pumps, sensors, valves
Engines come with hundreds of different accessories―making it all the more complex and demanding a task to maintain them quickly and reliably.
11.2017 | Text: Denis Dilba
Denis Dilba holds a degree in mechatronics, is a graduate of the German School of Journalism, and founded the “Substanz” digital science magazine. He writes articles about a wide variety of technical and business themes.
If you imagine an aero engine—with its compressors, turbines and combustor—as a human heart, then its accessories could be likened to the coronary blood vessels. Just as the human heart is surrounded by a network of arteries, the engine is surrounded by a range of supporting components. The analogy continues: accessories are split into numerous component groups that are critical to the functioning of the whole, as in the human heart. Should these accessories fail, the engine is at risk of suffering something akin to a heart attack: the engine can no longer operate safely and the aircraft must either perform an emergency landing or else remain grounded. Meanwhile, the costs incurred increase with every passing minute.
Christian Ludwig and his team are there to do all they can to avoid such a scenario. “And if it does happen, we’re the ones who can get the aircraft back in the air the fastest,” says the Director of Accessories Operations at MTU Maintenance Canada in Richmond. Here, right on the doorstep of Vancouver and its international airport, MTU has established its Accessory Repair Centre of Excellence (A.R.C.). Initially, the plan was simply to agglomerate accessories activities within MTU but, as the company continued to invest in the personnel and infrastructure required for accessories repair, it quickly saw the opportunity to turn it into its own, effective business.
Extreme complexity: engines come with hundreds of different accessories.
Starter for the V2500 and the GE90
Fuel-cooled oil cooler (FCOC)
Hydraulic pump for CF6 engines
Fuel pump for the CF6-80C2
Air-cooled cooler (ACDC)
Actuator for active clearance control
Valve for active clearance control
“The biggest challenge when it comes to accessories is the enormous complexity involved,” says Ludwig—a level of complexity that only a select few in the market have a handle on. One single engine has an average of 80 different accessories, manufactured by 15 to 20 different suppliers. The array of components ranges all the way from starter motors, fuel pumps, hydraulic pumps, actuators, sensors, and valves all the way to wiring harnesses and tubing. “When you’re catering to all sorts of different engine types, like we are, it quickly amounts to a bewildering array of hundreds of different accessories that you have to manage,” says Ludwig. Just the logistics of gathering together the individual parts required to repair a wide range of accessories is an enormous task in itself.
On top of that, you have to factor in the range of geographic and time constraints that come into play when you have repairs to be carried out, and you need to have experts on hand to do the job. “For instance, if an airline is flying to Hawaii and experiences a leaking fuel pump, they will need an operational replacement as soon as possible,” says Ludwig. “At the same time, we need to reserve enough capacity to deal with maintenance and repairs on engine accessories that come in as part of a scheduled engine shop visit.” Then there are accessories that need to be checked after a set number of hours in service. “We have to be able to cover all that work at the same time, or else our customers will lose interest,” says Ludwig.
450 repair procedures
Accordingly, the accessory repair process has to run like clockwork. “When an accessory comes in, an incoming test shows us what isn’t working. Then we take the unit apart and give it a good clean before we perform visual inspection and tests on the components,” explains Ryan James, who is responsible for engineering at the A.R.C. Repairs are then carried out, followed by reassembly and final testing, before the accessory is sent back to the customer. Repairs draw on some 450 different procedures. And if the repair work is taking too long, James’s colleagues will simply take a complete, functioning unit of the same model from storage, and send that back instead.
As a result, defective accessories can be replaced with functioning ones within between four and 24 hours. “With some airlines, we have agreements to keep replacement units for their fleets in central storage. From there, the units are put onto the next aircraft to land at the airport where the exchange is due to take place,” says James. “That’s when we achieve the four hour replacement rate.” But even the 24-hour turnaround time is often faster than what the competition can offer, competition that includes companies such as Lufthansa Technik, Allen Aircraft, AJ Walter and Triumph, as well as the manufacturers of the accessories themselves. The latter in particular often specialize in just a few accessories, and are slower in the decision-making process because of the size of their company. This means that they are rarely able to match the service offered by MTU’s A.R.C.
All-inclusive service package for accessories
The Canadians are also extremely flexible, offering accessory repairs for everything from business jet engines such as the CF34-3 to the mighty GE90 that powers the Boeing 777. “Our all-inclusive service package for accessories is particularly popular,” says Ludwig. This is a comprehensive service whereby MTU takes care of all an airline’s accessories. This includes the management of line replaceable units (LRUs), specific accessory components that can be replaced on location during routine operations. “This demanding service offering is possible only because around half of our employees in this segment work on site with the customer,” says Ludwig.
Everything points to growth. Last year, the A.R.C. repaired 11,000 accessories, bringing in business amounting to 60 million Canadian dollars. The 98 members of the A.R.C. team currently serve 114 customers, which include airlines, engine manufacturers and even the U.S. Air Force. “We’ve set our sights on almost doubling our revenues by 2020,” says Ludwig. In other words, business is booming.