Cargo nets are one of the most widely abused and most misunderstood components of the air cargo industry. Despite their almost universal usage in both lower deck and main deck cargo applications, even the most cursory ramp inspection will almost always turn up nets that are not in a condition to be used, or not fitted properly or in many cases all of the above.
The use of cargo nets came before the introduction of the 747 and other wide-body aircraft over 40 years ago. They were used for both military and commercial (narrow-body) cargo operations ever since the first palletized aircraft took to the air. The original nets were manufactured from webbing and were both exceptionally heavy and difficult to use. Modern day cargo nets have improved considerably. Nevertheless, any kind of cargo nets need to be treated with sufficient care to prevent unnecessary damage and used properly in order to fulfil their all-important safety function.
For the vast majority of personnel working in the air cargo industry, nets are seen as no more than a device to stop the load falling off the pallet during transportation. It would come as a surprise to them to hear that an air cargo net is in fact a piece of aircraft equipment with a design purpose to restrain the contents of a loaded pallet in place during extreme flight conditions. Nets are designed, tested and manufactured to meet some extremely high load conditions, a requirement they must meet throughout their operating life.
All cargo nets are designed and have the purpose of providing in-flight restraint. To that end, any cargo net must always be in an airworthy condition and must be correctly fitted over the load. Every cargo net must be designed and certified to comply with the requirements of TSO C90, which includes extensive load testing to prove the capability of the net.
This means that the care and operation of a cargo net should not be left up to guesswork or tribal knowledge. They should be carried out with a proper understanding of what is required and should follow established procedures. These procedures will vary between manufacturers but in general they can be considered to be:
As a textile item, cargo net is very vulnerable to poor quality handling. A walk around many cargo facilities will show that this is all too frequently the case. When not actually in place over a load, cargo nets should always be such that they are not exposed to unnecessary wear, tear, and damage. This means keeping nets away from ultraviolet light, away from grease, oil, or other types of contaminants, and not placed on the floor where they may be driven over by forklifts. Where the net is permanently attached to the pallet along one side, the body of the net should be placed towards the center of the empty pallet before the pallet is placed on a stack. Where the net is not permanently attached, it should be removed and placed in an individual bag for future use, stored and segregated by the airline.
A net shall always be in an airworthy condition if it is being used. The allowable damage on any cargo net is defined by the net manufacturer. This information can be found in the component maintenance manual (CMM), or, more conveniently, on the ODLN which can be found on most nets these days. The use of any net having damage outside these limits is not permitted and such nets should be removed from service and either scrapped or sent for repair. While nets can undergo quite extensive repairs in any properly authorized ULD repair facility, it is never acceptable to perform ad hoc on the job repairs using pieces of rope or similar materials. In some cases a damaged net may be temporarily returned to service by the use of temporary repair straps but such practices may only be done in strict accordance with the manufacturers’ instructions and using the manufacturers’ materials.
For a net to be airworthy, it must have a valid TSO label (tag) attached to it. Otherwise nobody can tell if the net is a genuinely airworthy piece of equipment or not. Any net missing its TSO label must be withdrawn from service. Many nets are fitted with a second TSO tag to protect the net against loss or damage to this essential piece of identification. Any pre-use check of the net must include a check that the TSO label is present and visible.
As with any other item of aircraft equipment, there is just one correct way to use a cargo net. Although if one carries out a ramp inspection of a couple of dozen loaded pallets, you could be forgiven for thinking this is not the case! The installation of any cargo net onto a loaded pallet must follow a defined set of steps:
- Place the net evenly over the load with the sides of the net hanging down equally on all four sides.
- Insert all the net fittings into the pallet seat track at the appropriate intervals. These double stud fittings should fit easily by hand. Do not use any kind of external force to push the fitting into place as it will be impossible to remove at the other end.
- Take up any loose netting on all four sides using the reefing hooks and carefully stow any loose netting so it cannot catch on other items.
- Close the corners of the net using lashing lines or lashing loops (depending on the type of net). The adjacent sides of the net should be brought together as evenly as possible. When this operation is completed, the end of the lashing line or lashing loops is secured.
- On properly netted load, the net should be just tight enough to be secure and not able to move around. It should not be tightened such that it raises the edges of the pallet or that it damages the cargo loaded on the pallet.
There are some general statements that apply across the entire industry when it comes to the handling and use of air cargo nets:
- Cargo nets are costly items that can only withstand a small amount of damage before losing airworthiness. The use of a knife to cut the net at any part of the process is likely to result in a non-airworthy net and, if it is permanently attached to a pallet, a non-airworthy pallet and net.
- Cargo nets are not throwaway items. Airlines spend considerable sums of money to own and operate cargo nets and they have the right to expect that their assets are treated with respect.
- A non-airworthy cargo net is unacceptable for operation and may well result in regulatory intervention if found during random checks.
- A net without a readable TSO label is not useable and must be withdrawn from service.
- “Double netting” is a practice where a second, fully serviceable net is placed over a partly damaged net. While this practice will ensure the airworthiness of the load, it is an inherently wasteful practice as all too often this second net will be taken off and lost at the destination.
To summarize, air cargo nets are items of aircraft equipment. They are required to operate in an airworthy condition and deserve to be used and cared for just like any other piece of aircraft equipment. Failure to do so can lead to unintended consequences.
EXAMPLES (GOOD AND BAD)
On the spot “repair” of a net using a piece of “local rope” is never allowed. Only repair methods and materials approved by the net OEM or the airline are allowed to be used.
A nicely fitted net –though it is a shame the owner airlines logo flag has been torn off.
A typical net ODLN.
Net nicely placed in center of pallet ready for storage.
Non permanently attached net stored in bag. Note the net TSO plate clearly visible for easy inspection.