Hangar designs continue to evolve. Ian Harbison reviews projects from three industry suppliers.

Butzbach

Hangar doors are generally designed to slide or fold and to enclose the end of a hangar. Occasionally, special design requirements mean that they have to be modified to suit a particular project.

In some cases, the door has to cater for different aircraft models. One such project for Butzbach was a modification to the Beluga hangar at Airbus in Toulouse. The current fleet of five aircraft, which are based on the A300-600, will eventually be replaced by the larger Beluga XL, based on the A330-200 freighter.

Aside from the large base aircraft, the cargo bay is 6m longer, 1m wider and 0.5m higher than the original, to allow a pair of A350 wings to be carried.

When the aircraft arrives in Toulouse, it is moved into the unloading hangar, to allow unloading in high wind conditions – the upwardly opening forward door could act like a sail – with the rear of the aircraft remaining outside. By using a customised cut-out, the doors can be tightly closed around the fuselage.

This has now been modified to take account of the different fuselage diameters of both Beluga variants. This will cover joint operations, the standard aircraft being retired by 2020, while he first Beluga XL arrives in 2019.

Another use of cut-outs is when an aircraft is too big for an existing hangar. Not surprisingly, this was the case with the A380. Butzbach supplied such a system to Lufthansa Technik in Hamburg and has recently supplied a similar system to the MRO’s facility in Munich for incorporation into existing doors.

Of course, the company continues to be involved in new hangar projects, the most recent being for Turkish Technic, at the recently opened new Istanbul Airport. This features 156m x 21.5m sliding doors at each end of the hangar, for easy aircraft movement.

These can be moved without power in extraordinary situations, like extreme wind conditions or a power loss. Extensive use of translucent fibreglass door material allows a large amount of sunlight into the hangar and lights up the interior evenly and without any glare.

Delivered to an extremely tight schedule, this project was not without challenges, and not just  for purchasing, production, engineering and assembly. The external influences of working on  such a large construction site could not be taken lightly and led to some delays that were outside the company’s control.

The fact that it was completed by the specified deadline was in huge part due to the 22 Butzbach fitters, who were working on both door systems simultaneously.

BuildAir Engineering & Architecture

BuildAir Engineering & Architecture dates back to 2001 and was started in Spain by professors of structural engineering from Barcelona UPC University, who had come up with the concept of buildings constructed by linking together identical inflated tubes.

The first examples of this modular approach were small scale, designed as promotional buildings at events like the Singapore Grand Prix.

The first entry into aviation came in 2013, says Felipe Cano, commercial director, with a project for Airbus at its military facility at Getafe, near Madrid. Originally, this was a single bay hangar, measuring 70m long x 54m wide, with a movable inflatable front door and an apse-shaped shelter in the rear.

This enabled line and heavy maintenance tasks to be carried out undercover, with a 23m clear height giving space for an aircraft on jacks.

As a perfect example of the flexibility of the system, the hangar was extended in 2015, enabling it to accommodate two aircraft, such as A310 or A400M. This was achieved by simply adding additional tube sections.

This increased the length by 40m to 110m, and the useful area from 3,560m² to almost 6,000m², making it the largest inflatable structure in the world.

The tubes are made from fire retardant PVC-covered fabric and are kept constantly inflated by two independent motors at a relatively low pressure of 20-30mb. Initial inflation in the construction phase takes about an hour.

There is a backup generator as well, although the structure will still be stable and safe with 50 per cent of the tubes deflated. Anemometer data is monitored and the pressure increased accordingly in high winds, ensuring rigidity.

The Getafe hangar has successfully survived sustained speeds of 90kph over 10 minutes and a peak of 110kph. Wind loading is taken into account in the design phase using CFD, but Cano points out that if the structure did collapse and touch an aircraft, the softness of the tubes would cause minimal damage.

An Automatic Control System performs real-time tracking of tube pressures, wind speed, fire detection and operation of the inflation motors operation, reducing the costs of preventive maintenance, and maximising the safety of the structure. This provides online information to any computer or smartphone.

A side benefit is that the material is completely transparent to radio electrical signals and so causes no interference to radar, ILS systems or aviation communications.

Another advantage is traditional foundation works are not required. Instead, ballasted containers, resin-set anchoring bolts, screw piles or movable platforms can be used, with subsequent savings in time and costs, and making these structures fully portable – total delivery time for the Getafe hangar was less than six months.

That means a hangar could be built on an existing area of apron, with only a series of 20mm screw holes being left behind, if the hangar has to be removed or repositioned.

The second project carried out by the company was a line maintenance hangar for Lufthansa Technik Budapest, which became operational in November 2014. This can accommodate any Airbus A320 Family of Boeing 737 aircraft and is 45m x 62m, with a useful covered area of 2,800m² and a working height of 18m.

The total delivery time of this hangar, from the signing of the agreement to its commissioning (including design, manufacturing, testing, transportation and installation), was just three months and one week. Installation took 20 days, compared to 25 days for the slightly larger Getafe hangar.

The company’s latest, and most ambitious project is for Saudia Aerospace Engineering Industries (SAEI), a subsidiary of Saudia Airlines based in Jeddah. Measuring 75m x 95m, with a 26.5m working height, it is capable of handling an Airbus A330 or Boeing 777-200ER aircraft, and will take the world record from Getafe.

Inflation and quality tests were carried out in June 2018 and it will be operational soon, the project having taken six months. A new section of apron was constructed as a base for the hangar

While an inflatable hangar could be seen as a temporary measure, both Getafe and Budapest were thoroughly checked and tested in 2017, and cleared for another two years of operation, totalling five years in service since they were erected.

Rubb Buildings

The latest project for Rubb Buildings is a 40m wide x 42m long hangar for light aircraft and helicopters located in the London area. Like the company’s last two commercial aviation projects, a helicopter hangar in Doncaster for the National Police Air Service, and a line maintenance hangar for Easyjet at London-Gatwick, it features modular office units attached to the side of the building to support MRO activities.

Michael Halpin, marketing manager, says there is strong interest from the market at present, which he puts down to the efficient design and building system employed by Rubb. In particular, in some cases there is no need for traditional ground works, which can represent up to 30 per cent of project costs.

Ideally, a Rubb hangar would connect on to a concrete up-stand ring beam, but other options include ballast weights for smaller hangars and ground anchors into an existing surface.

Further advantages of this system are fast construction times, reduced overall steel weight, and the ability to relocate if necessary – the easyJet hangar took six months to design, manufacture and build, and airport development plans call for it to be moved in the next few years.

The structure consists of fully welded galvanised frames and, if there is a need to expand a facility, this modular design allows the gable end portal to be removed, new sections installed and the portal repositioned.

The roof uses translucent membranes to allow natural daylight to illuminate the workspace while the white roof surface reflects heat.  Optional Thermohall insulation minimises heat transfer, prevents condensation, and virtually eliminates thermal bridging and air infiltration.

This combines a flame retardant heavy duty fabric as an outer layer, with high density glass wool insulation as the core, and a self-cleaning PVC fabric as an inner layer. Other options include a range of doors, ceiling-mounted HVAC, overhead cranes, fire -suppression systems and fall-protection equipment.

The company does have one major project in hand, a large widebody base maintenance hangar with doors at each end but the customer and location are still under wraps.