Air Transport Publications
Login   |   Register
jobs Jobs
events Events
My bookmarks

Packing light

STG Aerospace is preparing to supply complete cabin packages of its photoluminescent and LED lighting products, as Ian Harbison found out during an exclusive preview of its Innovation and Engineering Centre in Cwmbran, South Wales

The Innovation and Engineering Centre has been quietly running for 18 months, says Dr Sean O’Kell, Director of Innovation. The company is headquartered in Swaffham, Norfolk, where it has its main manufacturing base but, due to limited space, an alternative location had to be found for the new facility. After looking at a number of possible locations, Cwmbran was selected, even though it is some 400km away by road. A prime reason was its location between two aerospace clusters, one in Cardiff (British Airways Engineering, GE Aviation, Zodiac Aerospace) and the other in Bristol (Airbus, BAE Systems, GKN Aerospace, Rolls-Royce). This has worked well in attracting skilled staff, roughly split equally between the two clusters. In addition, some Welsh government funding was available. 


There are four laboratories at the Centre, reflecting the company’s specialist product lines. The chemical and mechanical labs work mainly on photoluminescence for emergency floor path lighting and safety signs, while the electronic and photometric labs are concerned with LED lighting.


Dr Andy Hallett is the Senior Research and Development Scientist for photoluminescent products and carries out constant experimentation on the composition of all the materials used for the saf-Tglo range of floorpath marking system. A recent achievement has been the invention of a blue colour glow, rather than the usual green, which received EASA approval in October 2016 for all Boeing and Airbus models (except the A350 and A380).


In daylight, the body colour of saf-Tglo blu is whiter than the traditional systems, meaning that when it is used with any translucent film or overlay, the result is a truer, brighter, cleaner colour. In darkness, the glow has a calmer, softer, more reassuring quality, but the blue wavelength also offers enhanced passenger perception of the floor path to a dark-adapted human eye.


Another aspect of his work is to study the competition. Recovered sections from a Chinese PMA copy show that the protective sleeve is likely to allow fluid ingress and that a variety of liquids – including red wine and cola – can cause discolouration and decomposition of the photoluminescent layer. This dangerously reduces the illumination levels in an emergency. Safety issues aside, there is no cost advantage as leasing companies would insist on saf-Tglo being fitted to the aircraft as part of the lease return conditions. In addition, the company has had a presence in the country for the past two years, as STG Aerospace (China) was established as a Wholly Foreign Owned Enterprise in Shanghai. A third facility is located in Miami, FL, to serve the Americas.


Hallett also manages the mechanical laboratory, which, among other things, is concerned with the protective sleeve used to house saf-Tglo. These are subject to wear and tear from passengers’ roller bags, and from catering trolleys in the galleys. Tests involve both abrasion resistance from rotating abrasing wheels and a more complex procedure where a galley cart with 100kg of weight on board is pulled across the covers up to 20,000 times. While a saf-Tglo sample showed no damage, a European competitor product showed clear signs of wear and tear.


Dr Lauren Fleming, Senior Research and Development Scientist, manages the photometric laboratory. Equipment here includes a goniophotometer to measure the uniformity and spatial distribution of the light emitted by an object at all angles, building up a 3D picture of the illumination. This has been invaluable in the development of the STG reading light (see page 30) as it has a very specific shape and size of light footprint.


An integrating sphere analyses the aspects of light related to colour, such as temperature, rendering and spectral output. Colour temperature is measured in degrees Kelvin, with LEDs typically being warm white (3,000K), neutral white (4,000K) or daylight white (6,000K). STG has found neutral white to be the best choice for aircraft cabins. It is cool, but not too cool, and promotes a feeling of relaxation. This is a continuation of STG’s previous studies into passenger preference, for light colour from a warm white, in a six-month trial in 2012. An initial white-only LED system called WhiteHawk was analysed on three Avro RJ100s operated by SWISS International Air Lines. Each aircraft had a slightly different colour temperature (cool, medium and warm) and surveys showed cool tended to make food look less appealing.


STG’s more recent studies have shown that this is directly related to the Colour Rendering Index (CRI), a quantitative measure of how faithfully a light source can reproduce colours in comparison with an ideal or natural light source (CRI 100). Historically, LEDs have not been very good at achieving high CRI scores. This is important as colour rendering can affect two of the most important factors within the cabin; high CRI makes food appear more appetising and helps to reinforce brand recognition by ensuring that passengers see seat colours, carpets and uniforms at their best. >>

To download the PDF file for this article, you have to pay the amount by pressing the PayPal button below!

Filename: Packing light.pdf
Price: £10

Contact our team for more information!

The Airlines channel

Industry blog
Highlights from the Cabin Refurbishment & Repair Conference


You must be logged in to post a comment.

Please login or sign up for a free account.

Disclaimer text: The views expressed in the above comments do not necessarily express the views of Air Transport Publications Ltd. or any of its publications.