The vast majority of Unit Load Devices (ULDs) used today are designed and sold as certified ULDs. That means they meet a minimum performance standard as defined by the relevant civil aviation authority, which in most cases is the FAA and EASA.
However, there are also plenty of non-certified ULDs in use, and this sometimes causes confusion to those who buy, lease or handle ULDs: What’s the difference?
In this article, we dispel six common myths circulating the standards of ULDs.
MYTH 1: The certification process for ULDs is just a box ticking exercise
False. Getting a ULD approved by a civil aviation authority is much more than bureaucratic expediency. It’s a process that can take several weeks, and it doesn’t always go smoothly. In fact, it can sometimes force the manufacturer to delay series production.
First, the manufacturer submits reams of evidence showing that all the materials and parts of the ULD meets a minimum performance standard, which includes:
- Environmental degradation (e.g. aging, UV radiation, weathering)
- Documentation (e.g. instruction manuals)
- Markings (ID codes and manufacturer plate)
- Fire safety
The evidence submitted by the manufacturer includes test reports, Finite Element Method analysis, and other technical and airworthiness product data evaluations.
These calculations are then scrutinised by the civil aviation authority. It must make sure the ULD, while restrained in the hold, will not compromise flight safety and is strong enough to contain the cargo inside (and meet other requirements as set out in the Technical Standard Order or Supplemental Type Certificate).
If the authority comes across elements of the ULD that require further verification, it will go back to the manufacturer and ask for more testing and analysis to be carried out. If the results are inadequate, the manufacturer may have to modify the design so that the elements in question meet the required standards.
Once the authority is satisfied with the calculations and approves all the compliance documentation, it issues to the manufacturer an approval letter (e.g. certificate). This authorises the manufacturer to fit the certified ULD with a TSO plate and to release the manufactured ULD with an Authorise Release Certificate (e.g. EASA FORM 1 and FAA FORM 8130-3).
These demonstrate that the ULD was manufactured in accordance with approved design data. There are currently three certification standards for ULDs: C90d - Cargo Pallets, Nets and Containers; C172 - Cargo Restraint Straps
Assemblies; and C203 - Fire Containment Covers. Any ULD that falls outside the scope of the standards, can be certified under a Supplemental Type Certificate (STC).
MYTH 2: Any cargo container that is not certified is considered a non-certified ULD
Incorrect. Cargo containers come in all shapes and sizes, ranging from a simple cardboard box and customised crates all the way through to active cool containers and fire containment containers.
But what distinguishes a regular cardboard box from a non-certified ULD is the fact that the non-certified-ULD still needs to meet minimum manufacturing standards (just not necessarily the same ones as a certified ULD).
MYTH 3: Non-certified ULDs don’t have to meet any standards
Incorrect. While it’s true that some aircraft don’t require certified ULDs to be loaded into their holds, that’s not to say that non-certified ULDs don’t have to meet any standards at all. To be used on civil aircraft, they still need to meet certain standards, for example, International Standard ISO 4118. This sets out specification and testing standards for non-certified Lower-Deck Containers.
MYTH 4: Certified ULDs are built to a higher standard than non-certified ULDs
Not necessarily. They may be built to different standards, but certified and non-certified ULDs are usually built to at least the same minimum standard.
This is not so strange when you consider that ULD manufacturers design and produce both in the same factory, often using the same concepts, materials and parts. Having two separate manufacturing processes simply wouldn’t be economical.
Despite the build standard being more or less the same in most cases, certified ULDs do have distinct advantages over their non-certified counterparts:
- They can be used on nearly all aircraft, even if the hold is not strong enough to contain the contents of the loaded ULD during extreme flight conditions.
- They can generally be loaded on to main-deck compartments, so they can be contoured to fit the curvature of the plane, providing as much cargo space as possible.
- They alleviate ULD managers of the need to have both certified and non-certified ULDs in their fleet to accommodate different aircraft types.
When you consider that many ULDs are transferred between different types of aircraft and even other airlines before reaching their destination, these are distinct advantages.
MYTH 5: Certified ULDs are much more expensive than non-certified ULDs
False. Usually, there is not much difference in price between certified and non-certified ULDs. After all, most ULDs go through a very similar manufacturing process, regardless of any certification that may or may not follow.
What affects the price more is the type of ULD. For example, an RKN container would normally cost more than an AMA main-deck container, due to the advanced technology used and its application.
MYTH 6: If you want a customised ULD, it has to be certified
Not true. There are situations when a ULD can be designed for a specific purpose and the aircraft manufacturer is willing to permit its use, even if it hasn’t been certified. The DRX container is a good example.
Developed by VRR, this large, unique non-certified ULD does double-duty. First, it allows the air transportation of highly dedicated and sensitive machinery. Second, it supports the use of high-tech equipment and provides workstations for personnel once in situ.
Although the DRX container is classified as a non-certified ULD, it’s permitted onto the B747F and B777F because its pallet base is certified by EASA. By using a certified base, VRR has enabled the attachment of a certified net.
It’s a clever workaround. The top part of the ULD (i.e. the container) is considered cargo and restrained by a certified net, which in turn is attached to a certified base. Hence, it is may be loaded according to the freighters’ WBM.
If you’d like to know more about certified and non-certified ULDs, check out Part 2 of this blog. Interested in a quote for a specific type of ULD? Drop us a line at email@example.com and we’ll get that arranged.