Introduction

Maintenance work on an aircraft can be large (deep maintenance) or may consist of minor inspections or repairs between flights (line maintenance). They can be broadly classified into engineering and refurbishment. The engineering work includes routine work and work to rectify the fault on the outside and inside of the aircraft. They can be performed in a hangar, at the airport or at the airport apron. Renewal may consist of removing paint, cleaning and painting all or part of the lining on the ship, and carrying out occasional work inside the ship.

Access requirements for engineering and refurbishment may also vary. For example, refurbishment may require wider working platforms at levels that are not always ideal for engineering. Renewal also requires a clearance between the aircraft and the build platform. The need to ensure safe access for all industries that may work with an aircraft requires careful planning and often changes in access as work progresses.

The dangers and risks associated with aircraft maintenance are similar to those found in construction. However, the non-linear shape of the workpiece (aircraft) and the importance of avoiding damage to its coating and structures pose additional risks.

Types of access devices

The industry uses a wide variety of access devices. These include suspended work platforms, specially built for aircraft refurbishment, platforms adapted in shape to all or part of the aircraft, service docks that can be adjusted in height and profile for different aircraft (e.g. bow and tail service docks), various types of scaffolding , mobile access platforms, towers and steps.

Specialized equipment in the form of docks is a significant investment, however, it can provide safe access as it allows it to precisely match the shape of the aircraft. The systems can be part of the hangar's equipment and can be used in many horizontal and vertical combinations.

More common are adapted docks and scaffolding, which are usually fixed mobile structures.

General rules

If special service docks are not available, the need to conform to a rounded body is one of the main problems in ensuring safe access to an aircraft. Great attention should be paid to detail to prevent significant and dangerous gaps (distances) between the aircraft and the working platform.

The following guidelines can ensure a safe workplace:

  • When planning access, consider the needs of all users.
  • Protect all edges with edge guards on working platforms, towers, scaffolding, etc., from which a fall could cause injury. (Typically, the fuselage of the aircraft will protect at least one edge.)
  • Aircraft fuselage openings, e.g. doors and cargo compartments, should be provided with an edge protector, a means of access meeting the standard discussed later in this document, or should be kept closed. Airplane door frame strips cannot prevent falls and are not an adequate edge protection. However, a proprietary open door protection system is available.
  • Edges from which objects such as tools and materials can fall out and cause injuries should be provided with toe boards. Places where loose items are stacked above the toeboards require additional protection. Such measures can also help prevent damage to the aircraft shell.
  • The space between the working platform and the aircraft may vary depending on the nature of the work being performed. However, it should be as small as practicable and should not be large enough to allow objects or people to fall. If this cannot be achieved, edge protection must be provided, including, if necessary, a toe board.
  • Precautions should be taken to prevent or mitigate falls when work is carried out on the shell of the airplane itself, e.g. work performed by maintenance people standing on the wings.
  • Scaffolding and other access devices should be stable. It is likely that the scaffolds will not be assembled in a generally recognized standard layout, so there should be evidence that strength and stability calculations have been made.
  • Access to scaffolding and platforms should be internal if possible, and the entrance to each platform should be equipped with a trapdoor. The device should be strong enough to withstand the weight of all materials and equipment to be received in this way.
  • In some cases concerning aircraft maintenance, it may be foreseen that the scaffolding will be complex enough for a competent person to draw up a plan for assembly, disassembly and use.
  • Regardless of how access is obtained, emergency escape measures should be considered. In most cases, the means of access / escape will not allow the same escape velocity in the event of a fire as conventional escape stairs. If inspectors have any doubts about the adequacy of the means of escape, they may wish to look at the employer's fire risk assessment. If it is unavailable or there is any doubt as to its adequacy, inspectors should contact the fire department.

Adapting to the shape of the aircraft

The following techniques can be used to better match the inside edge of the landing platform to the shape of the aircraft:

  • Plywood sections can be used to conform to the exact shape of the hull. They can be prepared before the arrival of the plane. This technique can be useful at the nose of an aircraft and for closing the space between the scaffolding and the sloped leading edges of the wings. Each plywood section should be suitably supported and strong enough to accommodate the assumed load.
  • Trapezoidal scaffolding, i.e. a rear stringer longer than the front, may be used to adapt the scaffold to the shape of the aircraft.
  • Platforms can be suspended so that the working platform is close to the hull. It may be necessary to make small changes to the height of the working platforms in order to accommodate workers without the necessity for them to make elevations which may place them outside the protection provided by the guardrails.

Customized platforms and scaffolding may need to be modified using the techniques described in 1-3 above if used for aircraft types for which they were not designed.

When removing paint, the use of a plastic film may partially obscure the scaffolding or work platform being used. It is therefore especially important to check the condition of the scaffolding or the working platform to ensure that they still provide the required level of fall protection.

Considerations for specific access methods

Service docks

Some service docks have a motorized positioning mechanism. Both the movement of the docks and the mechanisms themselves may pose health and safety hazards (e.g. falling from unsecured edges and danger of being crushed / trapped between the moving parts of the dock and the dangerous parts of the machinery that are part of the mechanisms). Hazards in the form of motorized docks must be assessed and controlled.

The use of mobile mobile platforms

In all cases, mobile access platforms should be suitable for the use for which they are intended. The most important points to consider are:

  • Can they offer safe access to the task (will workers have to lean too far out of the basket, or will the location of the mobile access platform make it unstable)?
  • Are they suitable for a given environment (e.g. protection against the formation of excessive paint mist or the ingress of flammable vapors may require inspection of mobile aerial platforms used for spraying paint)?

Access steps and platforms

Access steps and platforms offer flexible means of access to many areas of the aircraft. However, existing maintenance access steps and platforms may need to be modified to comply with applicable regulations.

There are European standards for aircraft ground handling facilities and equipment.

Inspectors can find several classic access steps and platforms, some of which can be extended over 2m. Not all are equipped with edge guardrails, although some have an adjustable guardrail on one side.

Safety barriers should be provided whenever possible, although this may mean that different devices are needed to gain access to different areas of the aircraft. Adjustable handrails may be appropriate for certain steps and platforms, especially where the aircraft provides edge protection for one or more edges.

Harnesses and safety lines

The provision of edge protection equipment may not be rationally possible for some short term tasks such as rivet inspection. Some of these activities can be performed using mobile mobile platforms. An alternative could be to use support devices which prevent the user from reaching an edge from which he could fall. Only when their use is not an option should fall arrest systems including full body harness and energy absorbing lanyards be considered.

Fall protection systems (including any horizontal lines used for anchoring) must be properly designed, installed, maintained, sized, and their use closely supervised. Users should be trained in the safe use and maintenance of the harness.

Where possible, the lanyard anchorage point should be above the wearer's head. Anchorages may be an integral part of the aircraft surface or part of the hangar equipment, e.g. a horizontal lifeline suspended from the structure. Under certain circumstances, mobile access platforms may be a suitable anchorage point for work performed from the plane of the airplane.

It is essential that a safe distance is kept to prevent the user from hitting the ground. Employers should take into account the deformation of the anchor points or the taut lifeline, as well as the impact of the arrangement of any installed energy absorbers. Substantial ground clearance may be required. For example, a system consisting of a full body harness and a two meter lanyard with an energy absorber anchored at the user's feet may require up to 5.25 meters below the anchorage point.

The type of harness also needs to be considered. The employer must know exactly what the harness is intended for: a support device (i.e. preventing the worker from assuming an unsafe position) or preventing falls (i.e. protection in the event of a fall). In the first case, the lap belt and lanyard provide an adequate level of security. In the latter case, a full body harness and energy absorbing lanyard will be required.

There shall be safe access for attaching the harness to the anchorage point. It is also required when working on the anchor points themselves.

An aircraft as a working platform

Access to the top of the plane can be difficult. These surfaces include the wings, horizontal stabilizers, the tail, and the top of the airplane. Service docks, scaffolding, mobile access platforms basket lift can be used to provide secure access for most tasks.

However, in a limited number of cases it is necessary to carry out work using the aircraft shell as a working platform. These may include line maintenance on the apron. Fall protection measures should still be provided.

Some companies allow the use of an airplane shell as a working platform if the worker is wearing a full body harness and an energy-absorbing safety line connected to the anchor point in the mobile aerial platform basket (i.e. the worker steps out of the aerial platform basket onto the aircraft shell).

This method of using a mobile platform carries additional risks. First, the anchor point in the basket cannot be designed to withstand the force generated by a human fall. Secondly, the magnitude and direction of the forces caused by the fall may cause the mobile platform to overturn.

This is why inspectors should not allow work to be performed in this way unless the company has determined that:

  • Fall arrest system anchor point can withstand the forces generated by a falling person;
  • The mobile access platform will remain stable in the event of a fall;
  • The fall prevention system is adequate (in particular, there is sufficient ground clearance).

Access equipment control and maintenance

If access is only partially constructed or is under modification, that part of the access that is not used must be restricted by clear signs and barriers. To ensure that this restriction is complied with, there should be sufficient supervision of employees.

An aircraft that is repaired / refurbished will normally provide edge protection on one side of the access devices. Severe falls have occurred when workers were working on platforms and mobile scaffolds that were not placed next to the aircraft (e.g. for cleaning purposes). If such devices are not located at the aircraft, they should be marked with warnings (eg "incomplete scaffolding") and access to them should be prevented (eg by chains at entry points). Alternatively, they may be secured in some other way, e.g. by providing an open edge protection by placing similar equipment against it.

Lifting devices

Periodic checks between thorough tests may be appropriate for some equipment. Inspectors can ask employers if they have considered this as part of the risk assessments for lifting equipment.

Shared hardware

Aircraft maintenance contractors may allow subcontractors to use their equipment. Alternatively, subcontractors may provide their own access facilities but allow personnel from other companies to use them.

The basis of the principle is that the parties should agree among themselves who is responsible for which aspects of the maintenance of the equipment.

There were accidents due to structural and mechanical damage. If inspectors find poorly serviced equipment on the tarmac, they should not be surprised that no one will be ready to take responsibility for this fact. Many companies can use it, perhaps even without the knowledge and consent of the actual owner.

If inspectors cannot identify who is responsible for the maintenance of the equipment, they can contact the managing body of the airport, which will normally be prepared to dispose of it as scrap.

Competencies

Employers should not allow anyone to engage in any activity related to work at height or with the use of equipment used for work at height, unless the person is competent to do so.

Where a company has specialized equipment, including equipment designed and built to be used only on one type of aircraft or on a limited range of aircraft types, personnel should have the appropriate competencies to identify and select the appropriate equipment for the particular aircraft and the task being performed.

Activities performed by inspectors

Inspectors are requested to use the standards detailed in this document when inspecting or discussing aircraft maintenance work at altitude.

Directness of risk

There is a risk of serious injury for people carrying out maintenance and renewal work on aircraft if the work is performed at heights.

There have been many serious and fatal accidents due to falls from service platforms, aircraft stairs and an open aircraft door. If the edges are not secured to the standards outlined in this document, inspectors should consider issuing a ban. The risk reduction measure can be as simple as placing existing safety rails on the working platforms, or using tower scaffolding or mobile mobile platforms, or as work platforms or edge protection.

Attention should be paid to risk control systems for equipment purchasing, servicing and careful testing, as well as training in equipment selection and use, edge protection maintenance systems and access restriction to an unsecured maintenance dock, and contractor management controls.