The DC-10 is just the latest in a long line of civil and military airframes to be pressed into service for firefighting duty, reports Mark Pilling

One of the most remarkable flight demonstrations at this year's show is 10 Tanker's DC-10 dropping its colossal load of 12,000gal (45,600 litres) of water right in front of the chalet line.


The firefighting aircraft, piloted by Capt Jack Maxey of Omni Air International, is making its first appearance in Europe to take part at Le Bourget. It is taking a break from an intensive US Federal Aviation Administration (FAA) flight and certification testing programme from its home base at Victorville airport in southern California.

The DC-10 Super Tanker has been in development for more than two years with input from the US Forest Service and the Tanker Board. The project is being spearheaded by a special purpose company called 10 Tanker STC, which is a joint venture between Omni Air International and Cargo Conversions.

Omni Air International is a Tulsa-based DC-10 and Boeing 757 operator that performs charter flights for tour companies, the government and other airlines. Cargo Conversions specialises in converting passenger airliners into all-cargo configuration.

The modification to the aircraft includes three external tanks under the fuselage, each holding up to 4,000gal of water. The tanks are basically the same as those developed for the Sikorsky S-64 Helitanker by Oregon's Erickson Air-Crane, says Maxey.

The tanks can be refilled on the ramp in 8min. The water drop is controlled from the flight engineer's position in the DC-10 using a computerised gravity feed system based on field-proven technology from Erickson. The water is dropped at flow rates up to 1,500gal/sec to achieve a fire coverage pattern desired by firefighters. Other fire containment applications can also be used.

The DC-10 converted for this mission "had been in operation with Omni for four years as a passenger aircraft but was retired and then pressed back into service for the tanker project about three years ago", says Maxey.

The Super Tanker is nearing the end of its certification test flights. It will require another 5-6 days of testing when the aircraft returns to California and will then undergo a C check. The FAA is expected to grant its Supplemental Type Certificate (STC) within a month. Certification will be inclusive of FAR 36 Stage III noise compliance.

The aircraft has been maintained to US FAR 121 standards since new, and will now be serviced on a Boeing-developed low- utilisation maintenance programme tailored to its new mission. It has an operational radius of 500nm (925km) when fully loaded and a ferry range of 3,000nm.


Drops can be made from as low as 150ft (45m) above ground level with a drop speed of 142kt (260km/h). Maxey's test team, which includes First Officer Tom Robbins and Flight Engineer Brad Pace, have conducted more than 30 drops so far with the aircraft. At the show it is restricted to making the drop from 330ft.

When the water is dumped, the flight profile of the aircraft is hardly affected. "It is not that big a deal," says Maxey. "The aircraft is very stable when we do the drop." Extensive proof-of-concept flying has been conducted since May 2003 using the converted aircraft and a DC-10 freighter at significantly higher weights than the Super Tanker will operate.

Interest in the aircraft has been high here at Le Bourget, says Maxey. 10 Tanker STC sees an initial market for several Super Tankers. In an area the size of the US or Australia, five aircraft could be positioned so that one could reach any fire within an hour.

Once the aircraft obtains its STC, the aim is to perform demonstration flights in conjunction with firefighting operators and the fire authorities.

Engineering support for the project has been provided by California-based Aircraft Technical Service. It handled the structural modification engineering including fuselage reinforcement and tank redesign and reinforcement, as well as co-ordinating the FAA certification work.

Source: Flight Daily News