Evergreen 747 Supertanker

747 Supertanker

Original 747-200 N470EV, tanker #947
Role	Firefighting
National origin	United States
Manufacturer	Boeing
First flight	FAA Certified October, 2006
Retired	N479EV 747-100 & N470EV 747-200
Status	One N744ST 747-400 operational^[1]
Primary user	Currently Global SuperTanker Services, LLC. Formerly Evergreen International Aviation (now defunct)
Number built	1 (active) 2 (retired)

The 747 Supertanker is an aerial firefighting aircraft based on a Boeing 747 widebody aircraft. Initially developed by Evergreen International Aviation, the first Supertanker was based on a 747-200 (N470EV, tanker/tail number 947), and never entered service. The second Supertanker (N479EV, tanker/tail number 979) was based on a 747-100 originally manufactured by Boeing in 1971 for Delta Air Lines.^[2] It entered service for the first time in 2009, fighting a fire in Cuenca, Spain, and made its first American operation on 31 August 2009 at the Oak Glen Fire.^[3]^[4]^[5] On December 31, 2013, Evergreen International Airlines filled a Chapter 7 petition in federal bankruptcy court in Delaware with all of the assets (including all 747 airframes) subsequently sold to a parts salvage re-seller, Jet Midwest Aviation.

As of August 2015, Global SuperTanker Services LLC (the successor to the defunct Evergreen Supertanker Services), has since purchased all the physical assets and intellectual property related to Evergreen’s original Supertanker (except the 747-100 airframe itself) from Jet Midwest. They have transplanted the existing sprayer tank system from the 747-100 into a newer Boeing 747-400 (N744ST) airframe.^[6]^[7]^[8]^[9]

The 747 Supertanker can carry up to 19,600 gallons (74,200 liters) of retardant or water for 4,000 miles (6,400 km), and is the largest aerial firefighting aircraft in the world.^[6]

Development

Development started after the 2002 fire season, which saw the fatal crashes of two air tankers in the United States. The accidents, involving a Lockheed C-130A Hercules and a Consolidated PB4Y-2, prompted the U.S. Department of Interior to issue an official Request for Information on next-generation airtankers.^[10]

Evergreen proposed to convert up to four of its Boeing 747-200 Freighters into massive 'Supertankers'. The first converted Boeing 747 (N470EV) made its maiden flight on February 19, 2004.^[10] The current Supertanker is N744ST, a 747-400.

By June 2006, Evergreen had spent $40 million on the project and was hopeful of both FAA certification and an evaluation contract from the United States Forest Service.^[11] In October 2006 the FAA issued Evergreen a supplementary type certificate for the installation and removal of internal tanks, associated systems and the support structure for the aerial dispersal of liquids.^[12]

An issue that impacted usage by the Forest Service was the U.S. Forest Service requirement for using fire retardant rather than water. When Evergreen attempted to convert the system from water- to retardant-dispensing, they encountered objections from the FAA. The FAA was concerned about the much greater density of fire retardant and the corresponding increased stress on the airframe. The FAA determined that the Supertanker's service life would be diminished and also raised concerns about the dangers of additional stress on the airframe during firefighting operations and heavy weight maneuvering.

Design

The 747 Supertanker during the 2010 Carmel forest fires in Israel

The Evergreen Supertanker is equipped with a pressurized liquid drop system, which can disperse retardant under high pressure or drop retardant at the speed of falling rain. This system allows the aircraft to operate within its design criteria.^[13] Using the pressurized system, the aircraft can deliver retardant to the scene of a fire while flying at a height of 400 to 800 feet (120–240 m), at approximately 140 kn (260 km/h, 160 mph), configured as if it were on approach for landing.

The Evergreen Supertanker’s tank system can be configured for segmented drops, allowing the contents of the tank to be released at multiple intervals while in flight.^[13] According to the company, the aircraft is capable of laying down a swath of fire retardant three miles (5 km) long and as wide as an American football field.^[14]

Because the tanker is based on an airliner, it can fly at speeds of around 600 mph (970 km/h; 520 kn) during cruise.

Operation

The Supertanker can operate from any airport with an 8,000-foot (2,400 m) long runway and suitable facilities. Evergreen identified several airports across the US that met or exceeded the criteria.^[13] In late 2009, the aircraft was under a call-when-needed (CWN) contract with Cal Fire and was stationed at McClellan Field outside of Sacramento, California.^[14]

Regulations allow for five individuals that are not crewmembers to be carried in the upper deck. This area could be used for command and control, mapping, incident monitoring and video/communications operations.^[15]

On 5 December 2010, the Supertanker was deployed to Israel to fight the Mount Carmel forest fire. This was carried out along with crew and utilities donated by other international fire agencies.^[16] On 9 June 2011 the Supertanker was also deployed to fight the Wallow Fire in Arizona, which was at 607 square miles (1,570 km²) burned and 0% contained at the time.^[17]

On November 24, 2016, the newer N744ST 747-400 Global Supertanker was deployed to Israel to help fight the wildfires raging in the northern port city of Haifa and elsewhere throughout the country.^[18]

Financial Difficulties

On 14 June 2013, the Supertanker received a call-when-needed contract from the United States Forest Service, despite not being flyable; the aircraft was sitting without engines at the boneyard and maintenance facility at Pinal Airpark outside Marana, Arizona, in need of a million-dollar “C” check and other maintenance. Because of financial difficulties, Evergreen deferred the maintenance, planning to have the Supertanker ready in time for the 2014 fire season.^[19]

On 30 November 2013, Evergreen effectively shut-down operations.^[20] In December 2013, Marana Aerospace Solutions of Arizona began to proceed with the sale of the Supertanker, in lieu of rent and other payments that Evergreen had failed to make. An involuntary bankruptcy case was filed against Evergreen later in the month, and then Evergreen itself filed for dissolution under Chapter 7 bankruptcy on 31 December 2013, freezing the sale.^[21]

References

External links

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