Preventing falls from height during aircraft maintenance
SIM 05/2002/52, previously SIM 07/2002/07 and 03/2002/13
This SIM provides guidance for inspectors on means of preventing falls from heights during the maintenance and refinishing of aircraft, and the standards to be applied. This guidance should be read in conjunction with OC 200/31 on The Work at Height Regulations 2005(WAHR) and related guidance. The heights involved in such work may be up to 18 metres. It does not cover access to helicopters, or military aircraft.
Introduction
1 Maintenance work on aircraft may be major (deep maintenance) or consist of minor checks and repairs between flights (line maintenance). It can broadly be divided into engineering and refinishing. Engineering work involves both routine and fault correction work on the inside and outside of the aircraft. It may take place in a hangar or on the airport apron. Refinishing may involve paint stripping, cleaning and painting of all or part of the exterior of the aircraft and occasionally interior work.
2 The environments in which deep maintenance and line maintenance take place can be very different. Deep maintenance invariably takes place in hangars, offering protection against the weather and with a limited number of vehicle movements. Line maintenance may take place outdoors, often on the airport apron, where weather conditions and the large number of vehicle movements are additional considerations.
3 The access requirements for engineering and refinishing can also be different. For example, refinishing work may require more extensive working platforms at levels not always ideal for engineering work. Refinishing work also requires a space between the aircraft and the working platform and the aircraft. The need to provide safe access for all the trades who may work on the aircraft requires careful planning and often changes to the access as work progresses.
4 The hazards and risks in relation to maintenance work on aircraft are similar to those found in construction. However, the non-linear shape of the workpiece (aircraft) and the importance of avoiding damage to its skin and structures pose additional risks.
Legal requirements
5 Each employer has a duty to ensure that access equipment is safe, so far as is reasonably practicable, for its employees and other people to use. Reasonably practicable, but suitable and effective measures should be taken to prevent anyone falling a distance that might cause them personal injury. OC 200/31 provides a guide to the WAH Regulations which consolidate existing duties and do not constitute any significant change to the way work at height risks are expected to be managed, inspected or enforced. This SIM highlights specific risks associated with work on aircraft and the precautions and standards to be expected. There is no reason WAHR cannot be applied to aircraft maintenance, although there will be some situations where avoiding work at height is not an option
6 The following legal requirements are relevant:
1) Work at Height Regulations 2005
2) Health and Safety at Work etc Act 1974 (HSW Act), ss.2, 3 and 4;
3) Management of Health and Safety at Work Regulations 1999 (Management Regulations) regs.3, 4, 5, 7, 10, 11, 12 and Schedule 1
4) Provision and Use of Work Equipment Regulations 1998 (PUWER);
5) Lifting Operations and Lifting Equipment Regulations 1998 (LOLER);
6) Personal Protective Equipment at Work Regulations 1992 (PPE Regulations).
Types of access equipment
7 A wide range of access equipment is used in the industry. This includes suspended work platforms specially built for aircraft refinishing work, decking that is customised to fit all or part of an aircraft, docking that can be adjusted in height and profile for a range of aircraft (eg nose and tail docking), various types of scaffolding, mobile elevating work platforms (MEWPs), towers and steps.
8 Special docking equipment (sometimes referred to as 'scene docks' or 'jigs') represents a substantial investment, but it can provide safe access as it can be adjusted to closely follow aircraft contours. Systems may be a part of the hangar structure and may be placed in a number of horizontal and vertical combinations.
9 More common are customised docking and scaffolds, which are usually permanent mobile structures.
General principles
10 One of the main problems in providing safe access to aircraft where special docking is not available is the need to follow the rounded body shape. Considerable attention to detail is needed to ensure that there are no significant and dangerous gaps between the aircraft and the working platform.
11 Reg 6 of the WAH regs sets out a hierarchy of measures to enable duty holders to select the most appropriate method of work in order to avoid or minimise risk associated with work at height. Schedule 2 to the Regulations sets out requirements for guardrails, toe boards etc. The following guidelines can provide a safe place of work:
1) When planning access, the needs of all users should be considered in order to ensure that Management Regulations reg.11 (cooperation and coordination) is met.
2) All edges of working platforms, towers, scaffold, etc from which any person could fall a distance liable to cause personal injury should be provided with edge protection. (Normally, the aircraft fuselage will provide edge protection to at least one edge).
3) Openings in the aircraft fuselage, eg doors and cargo holds, should be provided with either edge protection, a means of access meeting the standard as discussed in rest of this SIM, or kept shut. The straps provided to aircraft doorframes are not capable of preventing a fall, and are not suitable as edge protection. However, proprietary edge protection systems for open doorways are available
4) Edges that objects such as tools and materials could fall from and cause injury should be fitted with toeboards. Where loose items are stacked at heights above the toeboards additional protection may be required, akin to the 'brick guards' seen on construction sites. Such measures can also help to prevent damage to the skin of the aircraft.
5) The gap between the working platform and the aircraft may vary depending on the nature of the work being carried out. However, it should always be as small as reasonably practicable, and it should never be so large as to let people or objects fall through. Where this cannot be achieved edge protection, including where necessary a toeboard, should be provided.
6) Means to prevent or mitigate falls should be in place when work is carried out from the skin of the aircraft itself, eg work by operatives standing on the wings ( see paras 29-34 ).
7) Scaffolds and other access equipment should be stable. It is likely that scaffolding will not be assembled in a generally recognised standardised conformation so there should be evidence that strength and stability calculations have been carried out.
8) Access to scaffolds and decking should preferably be internal, and the entrance into each landing should be fitted with a trap door. The access should be strong enough to withstand the weight of any materials or equipment to be taken up by this route.
9) In some cases it is foreseeable in aircraft maintenance that the scaffolding will be of such complexity as to require an assembly, use and dismantling plan to have been prepared by a competent person.
10) However access is gained, means of escape in the event of an emergency needs to be considered. In most cases the means of access/egress will not allow the same speed of escape in the event of a fire, as would conventional emergency stairs. If inspectors are in any doubt about the adequacy of the means of escape they may wish to look at the employers fire risk assessment. If one is not available or if there are doubts about its adequacy, inspectors should contact the fire brigade as a matter of evident concern.
Following the aircraft shape
12 The following techniques can be used to obtain a closer fit of the inner working platform edge to the aircraft shape:
1) Plywood sections can be used to accurately follow the contour of the fuselage. Such sections could be prepared in advance of the aircraft arriving. This technique can be useful at the nose of the aircraft, and for closing the gap between a scaffold and the raked front edges of the wings. Any plywood sections should be properly supported and sufficiently strong to take the anticipated load.
2) A trapezium shaped scaffold, ie back ledger longer than the front, can be used to allow the scaffold to be shaped to the aircraft contours.
3) Platforms may have to be cantilevered to keep the working platform close to the fuselage. It may also be necessary to provide small increments in the height of working platforms to ensure workers are able to safely reach the aircraft without having to resort to step-ups and the like, which may place them above the protection afforded by the guard rails.
13 The customised decking and scaffolds discussed in paras 7-9 may require modification using the techniques listed in para 12 if they are used with an aircraft type for which they were not designed.
14 During paint stripping operations the use of plastic sheeting can partially obscure the scaffold or working platform being used. It is therefore particularly important that the condition of the scaffold or the working platform be checked to ensure it continues to provide the required level of protection against falls.
Considerations with particular access methods
Scene docks
15 Some scene docks are fitted with motorised positioning mechanisms. Both the movement of the scene docks and the mechanisms themselves can pose hazards to health and safety, (eg falling from unprotected edges and crushing/shearing traps between moving sections of the dock and dangerous parts of machinery which form part of the mechanisms). The risks of motorised scene docks should be assessed and controlled.
Use of MEWPs
16 Guidance on the use of MEWPs to allow access to the aircraft skin is given in paras 29-34 . (General guidance on the safe use of MEWPs is contained in OC 314/20 and MISC614 .)
17 In all cases the MEWPs should be suitable for the uses to which they are put. Key points to consider include:
1) Can they offer safe access for the task at hand (will workers have to lean too far out of the basket, will the position of the MEWP make it unstable)?
2) Are they suitable for the environment (for example, protection against overspray or ingress of flammable vapours may be required for the controls of MEWPs used in paint spraying)?
Access steps and platforms
18 Access steps and platforms offer flexible means of accessing numerous areas on the aircraft. However, existing maintenance access steps and platforms may require modification to bring them in line with current legislation. Paragraphs 29 to 37 and Appendix 2 of OC 200/31 contain guidance on WAHR in relation to working platforms, guardrails etc. General guidance on ladders and stepladders steps is found in Appendix 6 of OC 200/31 and Safe use of ladders.
19 There are European Standards for aircraft ground support equipment (GSE). BS EN 1915 covers basic safety requirements; BS EN 12312 - 8: 2005 covers specific requirements for aircraft maintenance stairs and platforms
20 Inspectors may find steps and platforms of some vintage, some of which may be extended to over 2 m. Not all are provided with guardrails to any of their edges, though some designs have an adjustable guardrail on one side.
21 In order to comply with WAHR guard rails should be provided wherever possible, even though this may mean that different pieces of equipment are required to gain access to different areas of the aircraft. Adjustable guardrails may be appropriate for some steps and platforms, especially when the aircraft provides edge protection to one or more edge.
Harnesses and lanyards
22 The provision of equipment with edge protection may not be reasonably practicable for some tasks of short duration, such as rivet inspection. It may be possible to carry out some of these activities from a MEWP. An alternative could be the use of work restraint that prevents a user reaching an edge from where they could fall. Only where this is not an option should fall arrest systems, incorporating a full body harness and energy-absorbing lanyard, be considered.
23 Fall arrest systems (including any horizontal lines used for anchorage) need to be properly designed, installed, maintained, kept well adjusted and their use should be closely supervised. Users should be trained in safe use and care of harnesses
24 Where possible the anchorage point for the lanyard should be above the wearer's head. Anchorage points may be integral to the aircraft surface or may be part of the equipment of the hangar, such as a horizontal lifeline suspended from the structure. In certain circumstances a MEWP may be a suitable anchorage point for work carried out from the aircraft surfaces (see paras 29-34) .
25 It is vital that the clearance distance is sufficient to prevent the wearer hitting the ground. Employers should take into account the deflection of the anchorage points or lifeline when put in tension, as well as the effect of the deployment of any energy absorbers that have been fitted. Considerable clearance may be required. For example, a system comprising a full body harness and 2 m long lanyard with an energy absorber anchored at the level of the wearer's feet could require up to 5.25 m of clearance below the anchorage point.
26 The type of harness also needs to be considered. The employer needs to be clear about what the harness is intended to do: work restraint (ie preventing the worker reaching a dangerous position) or fall arrest (ie protection in the case of a fall). For the former purpose, a waist belt and lanyard will normally offer an adequate standard of protection. In the latter case a full body harness and energy-absorbing lanyard will be required. OC 314/20 gives further advice.
27 Some companies have experimented with securing the harness to a vacuum pad attached to the surface of the aircraft. Tests have shown that the vacuum devices are effective anchorage points in dry conditions, but their performance can deteriorate sharply when the aircraft surface is wet or icy. Inspectors coming across vacuum systems being used should enquire whether the user has determined the performance of the device in adverse conditions - for example from the manufacturer's information or by testing).
28 Safe access must be provided to attach the harness to the anchorage point. Safe access will also be required during work on the anchorage points themselves.
The aircraft as a working platform
29 Access to the top surfaces of the aircraft can be difficult. These surfaces include the wings, horizontal stabilisers and tail, and the top of the aircraft (crown skin). For most activities scene docks, scaffolds or 'cherry picker' style MEWPs can be used to provide safe means of access.
30 However, in a limited number of cases it is necessary to work using the aircraft skin as a working platform. These can include some line maintenance on the aircraft apron. Means to prevent falls should still be provided. Solutions include:
1) Providing general access or tower scaffolding in the area to be worked on (eg at the leading and trailing edges of the wing);
2) Positioning MEWPs to act as edge protection at the edges from which people may fall (eg the leading and trailing edges of the horizontal stabiliser);
Work restraint;
4) Nets and airbags may have some application and need to be considered as part of the hierarchy of controls
5) Using a suitable personal fall arrest system anchored to an overhead horizontal line or other suitable anchorage point in a hangar; and
6) Vacuum pads (see para 27 ) - note these are just anchor points and can be used with both work restraint and fall arrest
31 It is important when using the measures in para 30(1) and (2) to ensure the scaffold or MEWP will remain stable should someone fall against, or into the platform.
32 Some companies permit the aircraft skin to be used as a working platform when the operative is wearing a full body harness and an energy absorbing lanyard connected to an anchorage point within the basket of a MEWP (ie the operative steps out of the MEWP basket onto the aircraft surface).
33 There are additional hazards that arise from using MEWPs in this way. Firstly, the anchorage point within the basket may not be designed to withstand the forces imposed by a person falling. Secondly, the magnitude and direction of the forces produced by any fall may cause the MEWP to overturn. Finally, the guidance on lanyards and harnesses in paras 22-28 should also be considered.
34 Therefore, inspectors should not allow work to proceed in this way unless the company have established that:
1) The anchorage point for the fall arrest system can withstand the forces imposed by a falling person;
2) The MEWP will remain stable should a fall occur; and
3) The fall arrests system is suitable (in particular, there is sufficient clearance to ground level).
Assessing risk of injury
35 Under the WAH Regs precautions are required where there is a risk of injury from a fall. The guidance in OC 200/31, the inspector briefing presentations and in the topic inspection pack should be enough to enable inspectors determine whether the risk of injury from falls has been adequately addressed. If inspectors find situations in aircraft maintenance where this guidance does not seem to apply they should seek advice from the Sector.
Inspection and maintenance of access equipment
General
36 Both WAHR and LOLER require inspection of access equipment. OC 200/31 Appendix 9 gives a checklist of inspections
37 Some employers at airports have little or no idea how much equipment they have, or where it is located. Such equipment is unlikely to be adequately maintained. Inspectors should therefore establish how owners keep track of the access equipment they own and what records are kept.
38 If access is only partly constructed, or is being modified, there must be clear signs and barriers demarcating the part of the access that is not to be used. There should be sufficient supervision of workers to ensure that the demarcation is being observed.
39 The aircraft under repair/refurbishment will usually provide the edge protection on one side of the access equipment. Serious falls have occurred when operatives have worked on decking and mobile access scaffolds which were not positioned next to an aircraft (eg in order to tidy up). When not against an aircraft, such access equipment should be marked with some form of warning (eg 'incomplete scaffold'), and have access prevented (eg by chains hung across the entry points). Alternatively, they may be made otherwise safe, for example by the provision of edge protection to the open edge, or butting up to the open edge of similar equipment.
40 Any pre-use inspection requirement for MEWPs should be laid out in the manufacturer or supplier's instructions, which can be quite detailed.
41 Lanyard and harness systems should be inspected and maintained. See OC 282/30 and INDG 367 , which contain further advice.
Lifting equipment
42 Some access equipment, such as MEWPs, is lifting equipment for the purposes of LOLER. Such equipment should be subject to a scheme of thorough examination. ( OC 314/20 provides further advice on LOLER).
43 Periodic inspections between thorough examinations may be appropriate for some equipment. Inspectors may wish to ask employers if they have considered this as part of their risk assessments on lifting equipment. Interlocks that prevent MEWPs being raised above a safe height (eg because stabilisers have not been deployed) are components that may benefit from such attention.
Inspections under CAP 642
44 The key industry guidance document, CAP 642 'Airside Safety Management', advises that vehicles and equipment that are issued with airside vehicle passes (AVPs) should be subject to periodic inspection by the airport operator or by companies approved by the airport operator. Implementation of this guidance by airports is not uniform.
45 Some employers may believe these inspections to be equivalent to inspection and thorough examination under PUWER and LOLER. However, inspectors should note some access equipment may not require an AVP, and so will not be subject to such inspections by the airport operator. Furthermore, the minimum standard advised by CAP 642 is equivalent to an MOT check. Such a check will not cover the means of preventing falls from access equipment, or the safety of lifting equipment.
46 CAP 642 also contains model safety inspection checklists. The relevant checklist for lifting equipment found in CAP, chapter 4 and appendix C 'Safety inspection. Vehicle mounted lifting equipment' is more detailed than an MOT check, and includes such items as 'fail-safe devices/limit switches'. However, these additional elements are unlikely to secure compliance with the thorough examination requirements of LOLER. The model inspection is a generic check that is not generated by a risk assessment and includes no consideration of conditions and frequency of use, or differences between designs of lifting equipment.
Shared equipment
47 Aircraft maintenance contractors may allow their equipment to be used by subcontractors. Alternatively, subcontractors may provide their own access equipment, but allow other companies' staff to use it. All employers who use work equipment will have responsibilities under WAHR and where relevant LOLER. The extent of this responsibility is a function of the extent of their control over it. As a basic rule, it should be clear between the parties who are responsible for what aspects of the equipment's maintenance. The guidance in this SIM at paras 5 and 11(1) remains valid for shared equipment.
48 Accidents have occurred due to the structural or mechanical failure of access equipment. If inspectors find poorly maintained equipment on the apron, they should not be surprised if no one is prepared to take responsibility for it. Many companies may use it; perhaps without the knowledge or consent of the actual owner
49 If inspectors are unable to establish who is responsible for the upkeep of the equipment, they can contact the airport operator, who will usually be prepared to remove the offending item as scrap.
Competence
50 Employers should not allow anyone to engage in any activity in relation to work at height or for equipment for use at height unless they are competent to do so. British Standard BS 8454:2006 Code of practice for the delivery of training and education for work at height and rescue gives guidance on training standards.
51 Competence is dealt with in OC 200/31 Appendix 8. Training for those assembling, dismantling or significantly altering scaffolding is outlined in WAHR Schedule 3, part 2, paragraph 12.
52 Supervisors and managers will need more in-depth training and must be able to recognise any inadequacies in equipment and in work practices.
53 Where a company has specialist equipment, including equipment designed and constructed for use with only one type of aircraft or limited types, staff should be sufficiently competent to recognise and select the right equipment for the aircraft and task at hand.
Interface with the civil aviation authority (CAA)
54 Regulatory oversight of the quality of aircraft maintenance in so far as this affects aircraft safety is the responsibility of the CAA. The Civil Aviation Authority approves aircraft maintenance companies under the Joint Aviation Requirements - 145 Approved Maintenance Organisations (JAR-145). This approval includes criteria on the adequacy of equipment and staffing, but only in as far as they affect the ability of the company to carry out work effectively and to the necessary quality to ensure aircraft safety.
55 The interface between CAA and HSE on aircraft maintenance is detailed in an annex to the Memorandum of Understanding (MoU) .
56 The Civil Aviation Authority have indicated that where their inspectors see unsafe acts, including the use of unsafe access equipment, they will comment to the employer concerned. As a result of the annex to the MoU, they will also bring such matters to our attention.
57 Inspectors should bring matters of concern with respect to the quality of aircraft maintenance, or other issues that may affect aircraft safety, to the attention of CAA. The Transportation Section can provide contact details. Inspectors should note contact with CAA in the Contact report for the incumbent whose equipment is the cause of concern, preferably using the words Regulatory liaison with CAA.
Further advice
58 Documents that give general advice on working at heights are listed at the appendix . Further guidance is also contained in various British and European standards on which the Transportation Section can advise. However, most of these documents or standards are not specific to aircraft access and will need to be interpreted in the light of the task and the law, as summarised earlier.
59 Advice on enforcement is given in paras 64 - 73 . The table describes a number of scenarios that inspectors may encounter where aircraft maintenance is being carried out. The intent of the tables is to aid the inspector when they are considering enforcement. The tables are for guidance only; any enforcement should be determined by the circumstances found on site.
60 Advice on aircraft maintenance undertaken at airports (both in hangars and on the ramp) can be sought from the Transportation Section. For advice on military aircraft maintenance at army, navy and air force bases, the Government, Defence and Education Section should be consulted.
61 Maintenance in any other location should be discussed with the Engineering Section of the Manufacturing Sector.
Action by inspectors
62 Inspectors are requested to:
1) Apply the standards detailed in this SIM when inspecting or discussing maintenance work at heights on aircraft;
2) Alert the Engineering and Transportation Sections any problems which arise from applying these standards, or any of the other advice contained in this SIM;
3) Draw to the attention of both the Engineering and Transportation Sections any new or innovative means of gaining safe access during maintenance work;
4) Advise CAA of any matters of concern relating to the safety of aircraft uncovered during inspections or investigations at aircraft maintenance companies;
5) Include the words Regulatory liaison with CAA in appropriate Contact reports when contacting CAA to raise an issue of concern.
Enforcement guidance
Immediacy of Risk
64 There is a danger of serious personal injury to persons undertaking aircraft maintenance and refinishing where this involves working at height.
65 There have been numerous serious and fatal accidents involving falls from maintenance platforms, aircraft steps and open aircraft doors. If edge protection is not provided to the standards outlined in this SIM, and it is reasonably practicable to do so, inspectors should consider issuing a prohibition notice (PN) as discussed in EMM section 4. Action to reduce the risk could be as simple as positioning existing guardrails on work platforms, or using tower scaffolds or MEWPs either as a working platform or to provide edge protection (mentioned below).
66 Consideration should be given to risk control systems for equipment procurement, maintenance and thorough examination, as well as training in selection and use of equipment, systems for maintaining edge protection and restricting access to unguarded docking, and management control of contractors.
Benchmark standards
67 Where there is a risk injury due to falling from height, the benchmark should be considered as a 'remote risk of serious personal injury'. If it is reasonably practicable to provide edge protection, the benchmark should be achieved by providing the standards at paras 10-34 and 36-53 .
68 Where customised docking is in use without adequate means to prevent access or falls, the benchmark should be considered as a 'remote risk of serious personal injury'. The benchmark should be achieved by providing the measures at para 38-39 .
69 Where there is work from heights below head height the benchmark should be considered as a 'remote risk of serious personal injury'. The benchmark should be achieved by considering the matters outlined in paras 35-54 .
Risk gap
70 The risk gap as derived from EMM Table 2.1 for key scenarios that inspectors may encounter is summarised below. The tables are intended to aid inspectors when considering enforcement and are for guidance only. Any enforcement should be determined by the circumstances found on site.
| Scenario | Actual risk | Risk gap |
|---|---|---|
| Inadequate edge protection at height (including work with aircraft doors open) - see paras 10- 34 | Probable risk of serious personal injury (SPI) | Substantial |
| Misuse of MEWPS - see paras 16-17 and 29-34 | Probable risk of serious personal injury | Substantial |
| Work at heights below head height in any location - see para 35 | Possible/probable risk of serious personal injury | Moderate/substantial |
| Work from customised docking and proprietary scaffolding equipment away from an aircraft such that there is an unprotected open edge - see paras 38 and 39 | Probable risk of serious personal injury | Substantial |
| Work restraint or fall arrest or restraint not worn or not clipped on - see paras 22-28 | Probable risk of serious personal injury | Substantial |
| Poorly maintained access equipment, damaged or missing edge protection. Other examples include structural damage and damage to base causing instability - see paras 36-41 | Probable or possible risk of serious personal injury depending on nature and extent of damage | Substantial |
Initial enforcement expectation (IEE)
71 The following are relevant in deriving the authority for standards for use in EMM Table 5.1 and hence for deciding the IEE.
- Work at Height Regulations 2005: Defined
- LOLER reg.5(1)(b) and ACOP para 144; reg.9: Defined
- PUWER regs.8 and 9: Defined
- Workplace Regulations reg.5(1): Defined
72 The EMM considers the risk assessment as an administrative measure and the standard 'defined'. The standard can be found in the Management Regulations and ACOP (L21) and any absence or inadequacies with an assessment should be considered using EMM Table 5.2.Strategic factors
73 A failure by inspectors to take enforcement action where the EMM and local factors indicate such action to be appropriate may have a negative impact upon employers' attitudes. This should be considered as a strategic factor for the purposes of EMM table 7.
Date first issued: 31 January 2002
Appendix: Guidance material
(para 57)
- Airside Safety Management CAP 642
- The work at height regulations 2005: A brief guide
- INDG 367 Inspecting fall arrest equipment made from webbing or rope
- HSE Information Sheet No. 614 Preventing falls from boom-type mobile elevating work platforms
- Fire Safety: An employers guide HSE 1999 ISBN 0-110341229
- British Standard BS EN BS EN 12312. Aircraft ground support equipment: specific requirements.
- Part 1:2001 Passenger stairs and
- Part 8:2005 Maintenance stairs and platforms
- BS EN 1915 Ground support equipment. General requirements
- Part 1:2001 Basic safety requirements and
- Part 2:2001 Stability and strength requirements, calculations and test methods.