Catering trolleys are a necessary evil for airlines. Despite stringent regulations and a growing need for security, they often form part of weight-saving initiatives in the cabin.

For a box on wheels, the regulatory requirements for cabin trolleys are strict. Not only must they meet fire, smoke and toxicity (FST) limits like any other cabin element, but they have to pass stress tests that ensure that doors stay closed on impact, as well as stability tests to prove the trolley will not topple over too easily.

In addition, they also have to be strong enough to withstand the abuse experienced over time from the repeated loading and unloading from catering kitchens; the transit to and from the aircraft; washing cycles after use; as well as challenges faced in flight, mainly as they are stowed, unstowed, and often crashed into seats.

Extra strength usually means additional weight. However, in recent years there has been a move away from traditional aluminium construction in favour of composites, especially as airlines demand lighter units to help reduce aircraft fuel burn.

As a result, weights have dropped from 30kg to 20kg, and even 15kg for ultra-lightweight designs – though a fully-loaded meal trolley must still carry up to 100kg.

To be fair to the designers, there are probably more constraints on trolleys than there are on many other pieces of galley equipment, generally because most have to conform to two industry standards – Atlas, which predominates, and KSSU – as well as not exceeding the width of the aircraft aisles.

Within these already strict limitations, there is a further requirement to also develop full- and half-scale trolleys, as well as other variants that meet different customer needs – including food, beverages, waste and onboard sales.

For the latter, Jamie Melleney, sales director at Direct Airflow, says demand is expected to slowly decline. Airlines are beginning to use the onboard IFE system as a product catalogue, giving passengers the option for home delivery.

This is something the airlines encourage, as carrying the goods on board adds extra weight; coupled with stricter certification requirements imposed on the trolleys due to the potential fire risk of the alcohol.

There will also be a need for additional security measures due to the high value of some of the goods available, such as jewellery and watches – this security could consist of extra physical or electronic locks, or RFID tags.

Thomas Koehler, vice president sales and business development at Norduyn, says composite construction offers advantages as it is transparent to the RFID scanner, unlike aluminium.

But Melleney notes that the same level of electronic scrutiny is still required throughout the airline’s network, in order to avoid trolleys ‘disappearing’ from the system at smaller outstations, which increases the investment required.

Koehler adds that the Norduyn trolley’s fully composite monocoque chassis and single opening front door provides enhanced passive structural security, which helps to prevent theft and is augmented by additional padlock fixing points.

There are several security systems on the market but the company has not partnered with any particular supplier, leaving the customer with maximum choice.

Of course, this additional security adds even more weight. Melleney explains that his company’s approach to weight saving was to work with its manufacturing partner, Korita Aviation, based in Suxhou, China.

The two companies worked together to source higher grade aluminium that retained the same strength levels as the original material, while also being lighter. Direct Airflow also selected lighter brakes and wheels, with further weight saving gained from using plastic brake pedals.

The new range, to be introduced in Hamburg at AIX 2015, includes a full trolley at 18.2kg (down from 21kg) and a half trolley at 11.3kg.

Koehler points out that there is a contradiction in the market – the demand is there for both the latest weight saving technology and smart solutions, yet there is a resistance towards the higher purchase price, with airlines tending to overlook the benefit of reduced life cycle costs through decreased maintenance requirements, as well as fuel and dry ice savings.

He says that the company’s Quantum trolley – which was developed in conjunction with Spiriant, a division of LSG SkyChefs using composite materials in its construction – has been very successful, with 37,000 currently flying with various operators, though there was less demand than originally expected.

In response, this year’s AIX will see the introduction of Quantum Flex, which he says offers the same benefits of reduced weight but at a more competitive price.

Also due to be launched at the show is a lightweight ATLAS polypropylene drawer; designed for reliability and durability, it can save around 2kg on a full size trolley. When used with ATLAS-standard Quantum and Quantum Flex trolleys, it can be extended and angled down for easy access to the contents.

In the process, it engages a hook system that uses the weight of the loaded drawer to pull the sides of the cart together from the bottom. This avoids the potential problem of the drawer coming off the runners as the side panels flex.

Options such as these allow both manufacturers to provide brand differentiation, with Direct and Norduyn going for push-to-close locking mechanisms and recessed locks, for example. Other typical options include dry ice drawers, pull-out or flip tables, chiller vents, and different grip handles.

Melleney explains that the market is driven by multiple factors. The aircraft OEMs prefer standardisation, as such new build aircraft tend to be equipped with galleys, and therefore trolleys, that have a limited range of standardised options approved for line fit.

These usually come from the main interior manufacturers. He comments that Airbus has introduced the SPICE galley concept to save weight and space, but the specified trolleys are not the standard size. This would mean the airlines would have to buy new equipment for the first shipset.

There is some reluctance in the industry to accept a limited range of standardised trolleys that don’t comply to the specific requirements of airlines and users, adds Koehler, most of whom require a full range of customisation options in today´s trolley manufacturers’ product portfolio.

For independent companies like Direct and Norduyn, this means sales opportunities arise when interior refurbishments are carried out, or when additional aircraft are added to the fleet.

Although it is not unknown for an airline to take the OEM-approved galley/trolley combination on the first aircraft, for the purposes of certification, then install its own choice of trolley on the rest of the fleet.