Antonov Airlines and Chapman Freeborn Airchartering have carried out a test flight to transport a capping stack by air instead of by sea.

According to Antonov, it worked with charter specialist Chapman Freeborn and its client Oil Spill Response Limited to deploy an An-124 to carry the fully assembled subsea capping stack and housing, which weighed 85.5 tonnes and measured 11.5 by 5.5 by 3.9 metres, to and from Stavanger in Norway. The test flight lasted an hour and 23 minutes.

“This was a very important test flight, as this represents the first time anyone has transported a capping stack on an aircraft that would be used in the event of an oil spill emergency, enabling a much quicker response anywhere in the world,” said Martin Griffiths, sales manager of the UK office at Antonov Airlines. “We faced a variety of challenges including limited clearance for the cargo, the weight and size of the capping stack itself and its effect on the flight, as well as the requirement to load it fully assembled, as would have to be the case in an actual oil spill scenario.”

The An-124 was chosen after an extensive logistics study by Chapman Freeborn because of its ability to travel up to 5,000 km with a 120-tonne payload, self-loading/off-loading capabilities and availability on the European spot market.

“When every minute counts, the number one priority is stopping the flow of hydrocarbons as quickly as possible. The ability to transport a fully assembled capping stack by air is a critical development for the industry,” said Chris Lund, technical manager of subsea well intervention services at OSRL. “Sea transport remains the most likely mobilization option for the majority of well sites, but for wells in more remote areas, this is a vital addition to our subsea capping and containment offering.”

Transporting capping stack equipment by air would traditionally have meant breaking it down into multiple payloads and reassembling it at the destination, before moving it to the incident site. For this test flight, OSRL had to design and build a bespoke frame with support from Trendsetter, the capping stack manufacturer. Engineers from Antonov Company’s design bureau also had to ensure proper distribution of the capping stack weight along the cargo cabin floor and acceptable minimal clearances from the cabin frames, while Antonov Airlines reviewed and approved the stress levels of the combined skid/capping stack design for the flight’s maximum G-forces.

“Chapman Freeborn has worked with OSRL for many years and we’re proud to have been involved in this industry-first test flight,” said Daniel Carriett, director of cargo operations at Chapman Freeborn. “We’re delighted to have successfully managed the project for our client and would like to thank Antonov and all of the other parties involved for their professionalism and support.”