Drilling and finishing holes in composite and/or metallic aircraft structures or components
Overview
This standard identifies the competences you need to produce and finish holes in composite and/or metallic aircraft structures or components, in accordance with approved procedures. It covers both fixed wing and rotary winged aircraft. The activities carried out will include the use of drilling machines and portable drills, using a range of cutters, as applicable to the type of hole and finish required. This will involve marking out, using the appropriate workholding arrangements and checking that the finished holes are to the correct specification.
Your responsibilities will require you to comply with organisational policy and procedures for the drilling and hole finishing activities undertaken and to report any problems with the activities, materials or equipment used that you cannot personally resolve, or that are outside your permitted authority, to the relevant people. You will be expected to work with a minimum of supervision, taking personal responsibility for your own actions and for the quality and accuracy of the work that you carry out.
Your underpinning knowledge will provide a good understanding of your work and will provide an informed approach to producing and finishing holes in aircraft structures or components. You will understand the drilling and hole finishing processes used and their application and will know about the tooling and ancillary equipment, materials and consumables, in adequate depth to provide a sound basis for carrying out the drilling and hole finishing activities, correcting faults and ensuring that the completed structures or components are to the required specification.
You will understand the safety precautions required when working with drilling machines and with their associated tools and equipment, especially those for isolating the machine during tool mounting and setting and when handling cutting tools and equipment. You will be required to demonstrate safe working practices throughout and will understand the responsibilities you owe to yourself and others in the workplace.
Performance criteria
You must be able to:
- work safely at all times, complying with health and safety and other relevant regulations, directives and guidelines
- confirm that the drilling machine is set up and ready for the machining activities to be carried out
- operate the machine tool controls safely and correctly in line with operational procedures
- drill and finish holes to the required quality and within the specified dimensional accuracy
- carry out quality sampling checks at suitable intervals
- deal promptly and effectively with problems within your control and report those that cannot be solved
- shut down the equipment to a safe condition on conclusion of the machining activities
- complete the relevant documentation, in accordance with organisational requirements
- leave the work area and structures/assemblies in a safe and appropriate condition, free from foreign object debris on completion of the activities
Knowledge and Understanding
You need to know and understand:
- the health and safety requirements of the area in which you are producing and finishing holes
- the importance of wearing protective clothing and equipment (PPE) and of keeping the work area safe and tidy
- the specific health and safety precautions to be followed whilst producing and finishing holes
- the hazards associated with carrying out drilling and hole finishing activities on aircraft structures or components and how to minimise them and reduce any risks
- the safety mechanisms on the equipment used and the procedure for checking that they function correctly
- how to stop the equipment in both normal and emergency situations and the procedure for restarting the equipment after it has been stopped in an emergency
- how to obtain and interpret drawings, standards, quality control procedures and specifications used for the drilling and finishing of holes (such as BS, ISO or BSEN standards, symbols and terminology and other documents needed)
- how to carry out currency/issue checks on the drawings and specifications you are using
- the importance of producing holes to the correct surface finish values and the methods used to achieve this
- how surface finish values are measured and/or compared and the type of equipment that is used
- the principles of limits and fits and their relationship in determining the final hole size
- the methods, techniques and equipment used to mark out and position components prior to drilling and finishing holes
- the different types and applications of drilling equipment (such as bench/pedestal, portable, spacematic, rackfeed, pneumatic, hand held pneumatic drills, pecker and positive feed)
- types and application of hole cutting and finishing tools (such as drills, reamers, counterbore, countersink and spot-face cutters)
- how to handle and store drills and finishing tools, safely and correctly
- the effects of clamping the workpiece in a jig/workholding device and how this can cause distortion in the finished components/structures
- why tool/equipment control is critical and what to do if a tool or piece of equipment is unaccounted for on completion of the activities
- the different types and application of cutting fluids
- the cutting characteristics of different materials and how this effects factors including selecting tool type and geometry, cutting speeds, lubrication and surface finish
- the principles and effects of cold working when finishing holes in aircraft structures or components
- the methods used to prevent corrosion on completion of drilling and finishing operations
- the quality control procedures used, inspection checks to be carried out on finished holes and the equipment to be used
- action to be taken in the event that holes fail to meet specification
- the problems that can occur with the drilling activities and how these can be overcome
- the extent of your own responsibility and to whom you should report if you have problems that you cannot resolve
Scope/range
Scope Performance
Carry out all of the following during the drilling and finishing activities:
- plan the drilling/finishing activities prior to beginning the work
- obtain and use the appropriate documentation for the drilling/finishing activities (such as drawings, job instructions, specifications, aircraft standards)
- adhere to procedures or systems in place for risk assessment, COSHH, personal protective equipment and other relevant safety regulations and procedures to realise a safe system of work
- obtain the correct tools and equipment for the activity, and check that they are in a safe, tested and usable condition and within current calibration date
- obtain clearance to work on the aircraft and ensure the safe isolation of equipment (such as mechanical, electricity, air or fluids), where appropriate
- provide and maintain safe access and working arrangements for the area in which the drilling/finishing will take place
- follow safe practice/approved drilling/hole finishing techniques and procedures at all times
- deal with defects in materials, components and equipment, in accordance with specified procedures
- dispose of waste items in a safe and environmentally acceptable manner, in line with company procedures
- return all tools and equipment to the correct location on completion of the activities
Use five of the following types of marking-out/setting equipment:
- rules/tapes
- squares
- Vernier instruments
- slip gauges
- protractors
- electronic feeler gauge
- approved aero markers
- feeler gauges
- dividers/compass
- jigs for marking out
- scribers
- templates
- through skin sensor (TSS)
- laser tracking
Use a range of workholding/guiding devices, to include five of the following:
- jigs/fixtures
- slave bolts
- gripping pins
- profile boards
- drill bars
- dowels
- jig pins
- drill blocks
- clamps
- ream blocks
Produce and finish holes in aircraft structures or components, using six of the following:
- bench/pedestal drill
- rackfeed drill
- pistol pneumatic drill
- angled pneumatic drill
- portable/rechargeable drill
- pecker drill
- straight pneumatic drill
- positive feed drill
- `spacematic' drill
- radial arm drill
- cold working pack (split sleeve and split mandrel)
- automated drills (such as vertical/horizontal plane and special drills)
- robotic drill
Produce holes in aircraft structures or components, using three of the following types of drill bit:
- twist
- cobalt
- piloted carbide core
- diamond coated
- core
- stepped
Produce and finish holes in two of the following materials:
- aluminium alloys
- composites
- titanium
- other specific ferrous, non-ferrous or non-metallic material
Carry out all of the following during the production and finishing of the
holes in the aircraft structures or components:
1. mark out, position and secure the item to be drilled, in accordance with company procedures
2. use the specified techniques and procedures to produce and finish holes
3. select and use the correct cutting feeds and speeds
4. use appropriate and adequate lubrication/coolant
5. check that positional accuracy complies to specifications
6. ensure that machined features are free from tool marks, burrs and sharp edges
7. apply surface protection/coatings to finished holes on completion of the drilling activity (where appropriate)
Produce and finish holes in aircraft structures or components, to include six of the following:
- through
- spot faced
- blind
- tapered
- stepped
- bored
- reamed
- dimpled
- counterbored
- holes with formed edges (such as radii)
- threaded (insert)
- holes with clearance fit
- de-burring
- holes with interference fit
- countersunk
Check that finished holes meet the required specification, using four of following:
- plug gauges
- depth gauges
- hole gauges
- de-burring/chamfer gauge
- Vernier gauges
- dial test indicators
- countersink check bolts
- surface comparator plates
- down-size dummy check bolts
- company-specific gauges
Produce finished holes which comply with one of the following standards:
- Civil Aviation Authority (CAA)/European Aviation Safety Agency (EASA)
- Ministry of Defence (MoD)
- Military Aviation Authority (MAA)
- Aerospace Quality Management Standards (AS)
- Federal Aviation Authority (FAA)
- BS, ISO or BSEN standards and procedures
- customer standards and requirements
- company standards and procedures
- manufacturers standards and procedures
Complete the relevant paperwork, to include one from the following and pass it to the appropriate people:
- build records
- job cards
- log cards
- aircraft flight log
- other specific recording method
Scope Knowledge
Values
Behaviours
You will be able to apply the appropriate behaviours required in the workplace to meet the job profile and overall company objectives, such as:
- strong work ethic
- positive attitude
- team player
- dependability
- responsibility
- honesty
- integrity
- motivation
- commitment