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Specialised equipment keeps aviation parts clean

19 April 2018

Richard Bastable, director of the Parts Cleaning Innovation Platform at NCH Europe, explains the challenges of cleaning parts in the aviation industry and outlines some of the factors maintenance staff need to consider.  

The subject of aircraft cleaning is so complex that the World Health Organisation has published a magnum opus on the subject called ‘A Guide to Hygiene and Sanitation in Aviation’. 

The guide points out that cleaning and disinfection on aircraft require special attention, as it is necessary to use agents that are not corrosive or otherwise detrimental to aircraft components. For example, it says 'not all effective cleaning disinfecting agents can be used in the aircraft cabin'.

Demands from the aviation industry take two forms: one consists of regulations; the other consists of the manufacturer's specifications for products that will work safely with its aircraft. Maintenance engineers should consider both sets of demands when choosing the cleaning agent and the cleaning equipment.

Two regulations are particularly relevant: EU 1321/2014, which looks at the airworthiness of aircraft and EC 216/2008, which brings together the common rules in the field of civil aviation.

These rules stipulate that when aircrafts and their parts are cleaned 'the maintenance programme must contain, in particular, maintenance tasks and intervals, especially those that have been specified as mandatory in the instructions for continuing airworthiness', and that 'the aircraft must not be operated unless it is released to service by qualified persons or organisations'.

Different cleaners can react differently to different grades of aluminium, steel, silicones, plastics and rubber seals, causing wear, etching, or corrosion to the material, something that could potentially render an aircraft non-airworthy.

Methods and checks 

The cleaning method is critical too. Manual hand cleaning, using stiff-bristled brushes can leave microscopic scratches, forcing contaminants deeper inside the component, reducing its lifespan and causing a potential risk to airworthiness.

Aircraft maintenance checks are usually carried out at set intervals, and follow a staged process. At each stage, the aircraft will be towed into a hangar to be cleaned and serviced. Checks are carried out after anywhere from 500 flight-hours — where routine maintenance might take 10h to complete — to 50,000 flight hours, where maintenance can last months and involve a complete overhaul and engine rebuilds.

Maintenance engineers are responsible for a variety of tasks such as disassembling the wing section to clean the actuator that controls the flaps, cleaning brakes, engine parts, seats or landing gears, to more complex tasks such as overhauling a Rolls-Royce turbojet engine. 

NCH Europe's Parts Cleaning Innovation Platform recognises that cleaning any aircraft requires a two-pronged approach – having the right cleaning agent, and having the right type of cleaning machine that will clean a variety of parts.

The company has developed a range of solvent and water-based degreasers that work with aviation approved chemistries. Hydrocarbon-based D60-rated cleaners, for example, offer a high flash-point for reduced flammability; the added benefit of military-spec performance means they are suitable for even the most demanding applications.

However, having a good cleaning agent is worthless if engineers cannot clean parts effectively. This is why NCH Europe has introduced parts-cleaning equipment that includes everything from a basic sink-on-drum manual hydrocarbon cleaner to fully automatic water-based machines that use high pressure jets to get the cleaning agent into even the most difficult-to-reach areas. At all times the equipment and cleaning agents are meeting the requirements and regulations of the aviation industry.

The largest standard parts cleaning machine from NCH is 1.2m wide and will accommodate parts weighing up to 200kg. We've also built bespoke equipment for companies in the aviation sector based on the frequency, volume and complexity of their cleaning requirements.

Cleaning and maintenance in the aviation industry doesn't need to be difficult: By choosing specialised parts-cleaning equipment and combining it with cleaning agents that meet aviation approved chemistries, maintenance engineers can ease the challenge of cleaning, even if – as with the Boeing 737 – there are 367,000 parts to get through.