Plastic media stripping facility for Tri-service helicopters

Citation

(1998), "Plastic media stripping facility for Tri-service helicopters", Aircraft Engineering and Aerospace Technology, Vol. 70 No. 6. https://doi.org/10.1108/aeat.1998.12770fab.005

Plastic media stripping facility for Tri-service helicopters

Plastic media stripping facility for Tri-service helicopters

Keywords Stripping, Vacu-Blast

Vacu-Blast, part of the USF Surface Preparation Group, is to supply a "whole aircraft" plastic media stripping (PMS) facility to the Naval Aircraft Repair Organisation (NARO), Fleetlands, Portsmouth. This follows the proven operation of similar PMS facilities by the Royal Air Force at RAF St Athan in South Wales and RAF Kinloss in Scotland.

NARO undertakes work for all three services ­ the Royal Navy, the Army and the Royal Air Force ­ and the facility will be used for the controlled stripping of paint and other surface coatings from complete helicopter fuselages, mainly from Sea King, Lynx, Chinook and the new Merlin (EH101) aircraft, during regular repair, overhaul and re-paint operations. The facility will also be used to strip coatings from critical mechanical parts prior to non-destructive testing.

The PMS process can be controlled closely to remove coatings selectively layer by layer, when required, and does not damage delicate substrates such as anodised surfaces. It also has inherent health and safety and environmental benefits, since no potentially hazardous chemicals or liquid effluent are involved.

Housed in a new surface finishing complex at the Fleetlands site, the PMS enclosure will measure 23 metres long × 7 metres wide × 8.5 metres high and will incorporate the "Waffle-Floor" pneumatic blast media recovery system, a Vacu-Blast invention.

The Waffle-Floor system utilises a constant downdraught of air which continuously directs used blast media, dust and debris through a heavy duty floor grille into a series of under-floor "mini-hoppers". These are connected to a common duct through which the material is conveyed pneumatically to the generator-reclaimer. This automatically recycles reusable blast media to the blast nozzle, thereby minimising media consumption. Degraded material and debris are directed into the dust collector for safe disposal as dry waste.

Because there are no moving parts, the system is said to be virtually maintenance-free and the floor design removes the need for pre-loading with non-recoverable blast media. The under-floor hoppers and ductwork are automatically purged free of blast media, which allows the media grade to be changed easily. The constant downdraught of air has the advantage of enhancing operator visibility.

In the case of the Fleetlands facility, the Waffle-Floor grid sections and connecting ductwork will be incorporated into the existing concrete floor of the hangar and will be able to withstand a load of 5,000kg, transmitted through an aircraft jack with an 8-inch diameter footprint.

Other features of the NARO facility include high-integrity media/debris separation to ensure that only good quality plastic media are recycled and process consistency maintained, in-process monitoring of media flow, and the use of acoustic construction techniques to minimise noise levels. The enclosure will incorporate heating and cooling for the comfort of operators and all processing parameters will be controllable from an external console situated by an observation window.

Although the Vacu-Blast facility will use high-quality thermoplastic acrylic abrasive media, the design of the blast generator and recovery system allows for the possible future use of an alternative starch-based media which has different flow characteristics.

The facility will be supplied by Vacu-Blast as a turnkey installation, including site preparation, operator and maintenance training and commissioning.

Further information is available from USF Vacu-Blast Ltd. Tel: +44 (0) 1753 526511; Fax: +44 (0) 1753 538093.