How should aircraft hangar doors be specified?

The correct specification for an aircraft hangar door is a coordinated schedule covering the aircraft envelope, door arrangement, structural interfaces, operating equipment, safety systems and project requirements. It should be prepared from the hangar layout and the aircraft’s actual movement route, rather than selecting a door from the nominal building dimensions alone.

Start with the aircraft envelope

Record the maximum overall length, wingspan, tail height, rotor diameter where relevant, and the clearance needed for towing or manoeuvring. The opening must accommodate the aircraft at its most restrictive approach angle, not only when it is positioned squarely in front of the door. Include clearance for towing equipment, wing walkers, ground-support equipment and any temporary loads that may pass through the opening.

Specify the finished clear width and height between obstructions. Tracks, guides, seals, framing members, lighting, sprinklers and projecting hardware must not reduce the usable opening. The specification should distinguish between the structural opening, the door leaf dimensions and the clear passage available after the door has been installed. This prevents an apparently adequate opening from becoming restricted by the operating gear.

Choose the door arrangement to suit the building

Horizontally sliding doors are commonly considered where there is sufficient side wall or apron space to stack the leaves. They can be suitable for wide openings, but the available side room, level running surfaces and wind exposure need to be checked. Bi-fold doors use hinged leaves that fold upwards and can reduce the amount of space needed in front of the hangar, although they require suitable headroom and substantial support at the upper frame.

Vertically lifting doors can preserve space around the entrance, but their guides, lifting equipment and supporting steelwork must be designed as part of the building. Rolling or sectional arrangements may be appropriate for smaller openings or ancillary areas, while a large main aircraft entrance may require a different solution. The choice should be based on the opening size, surrounding apron, roof geometry, wind conditions, available power and the required movement sequence.

Coordinate the door with the steel frame

Door tracks, hinges, lifting points and guide posts transfer forces into the surrounding structure. The drawings should identify these connection points and state the imposed dead, operational and wind loads so that the building frame, lintels, columns, rails and foundations can be designed accordingly. A door should not be treated as a lightweight fit-out item where its leaves or operating equipment are supported by the hangar structure.

Allowances are also needed for construction tolerances, movement of the steel frame, differential deflection and settlement. Tracks must remain aligned under the loads expected during operation. Threshold details should provide a firm, level route for aircraft wheels and towing equipment while allowing rainwater to drain away without creating a trip or equipment hazard.

Specify the operating system precisely

State whether the door is to be manually operated, electrically powered or fitted with another powered system. For powered doors, define the normal control position, control sequence, opening and closing indication, emergency stopping method and arrangements for opening the door if the normal power supply is unavailable. The operator should have a clear view of the movement area, or the design should include suitable monitored controls and warning systems.

Where a door is divided into multiple leaves, specify whether the leaves must move together, in sequence or independently. The schedule should also identify locking positions, end stops, travel limits and any interlock with lighting, ventilation, aircraft handling equipment or other doors. Controls should prevent an unsafe movement sequence, such as attempting to operate a door while a person or vehicle is within a protected travel zone.

Define safety measures through a risk assessment

Large moving doors require protection against crushing, shearing, trapping and unintended movement. Depending on the design, this may include guarded moving parts, edge-sensitive safety devices, obstacle detection, emergency-stop controls, audible or visual warnings, anti-drop protection and secure manual-release arrangements. The selected measures should be recorded in the risk assessment and reflected in the operating instructions.

Consider the likely presence of pilots, engineers, visitors, vehicles and ground crews. A separate pedestrian door may be needed so that people do not use the main aircraft opening as their routine access route. Its position, threshold, locking and escape function should be coordinated with the fire strategy and the building’s wider access arrangements.

Specify weather performance and environmental resistance

Door leaves, frames, seals and guides should be selected for the site’s exposure to wind-driven rain, temperature changes, airborne dirt and possible aviation-related contaminants. The schedule should describe the required resistance to water penetration and air leakage, together with the treatment of joints, meeting stiles, lower edges and side guides. A sloping apron, drainage channel or threshold detail may be necessary to keep surface water away from the interior.

Material and finish requirements should reflect the hangar environment. Steel components may require an appropriate protective coating, while areas exposed to moisture or chemicals may need additional corrosion protection. If the hangar is heated or used for temperature-sensitive work, include insulation and sealing requirements for the door leaves and perimeter. These choices affect the door’s weight, operating forces and supporting structure.

Separate security from operational access

Specify how the closed door is to resist unauthorised opening and how authorised users will be identified. Options may include mechanical locking, controlled key access, coded controls or integration with the site’s wider access system. The arrangement should not allow security features to prevent safe emergency release or leave the door unsupported when disconnected from its drive.

Where aircraft, fuel, tools or other valuable equipment are stored, consider the strength of the leaves, locking points, control cabinets and adjacent personnel doors as one security zone. Any glazing or vision panels should be positioned and protected to provide useful visibility without creating a weak point.

Set out the information required from the door supplier

A useful door schedule should include the finished clear opening, overall door size, leaf arrangement, stacking or lifting zone, operating method, design loads, finish, insulation, seals, drainage, power requirements, control equipment and safety devices. It should also show the door in plan, elevation and section so that the architect, structural designer, electrical contractor and building installer are working from the same information.

Before manufacture, review the door against the aircraft dimensions, hangar floor levels, apron formation, roof services and intended handling equipment. The final handover information should include operating instructions, isolation procedures, inspection points, safety-test requirements and replacement parts information. This documentation allows the owner to manage the door safely and maintain the installation in accordance with the specified design.