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The first "air drop" was made on the Mendenhall
Fire, August 12, 1955, on the Mendocino National Forest. The first operational air tanker was developed in Willows,
by the Willows Flying Service in 1955, at the request of the
Fire Control Officer for the Mendocino National Forest. A
Boeing Stearman 75 "Caydet" Agricultural Aircraft was modified with a 170 gallon
tank at the Willows airport. This Aircraft, N75081, became the first registered free fall air tanker in the history of aviation.
In 1956, seven agricultural aircraft were modified and
formed the first operational air tanker squadron in the United
States. Piloted by local aviators, this squadron operated out of the Willows Airport
fighting wildfires throughout California. Initially, plain water was used as the fire suppressant. However, it was soon discovered that most of the water evaporated before reaching
the fire, so the practice was adopted of adding chemicals
to the water to inhibit evaporation.
Borate was one of the first chemicals used, hence the
derivation of the term "borate bomber."
In 1959, heavy air tankers, capable of carrying 2,000
gallons of fire retardant, were providing an effective tool
in controlling wildfires.
Enter the A-26 Invader........
Ever since N5457V, the first A-26 converted to a fire tanker
by Aero Atlas back in 1959, this highly manoeuvrable, single pilot, Ex-WWII attack aircraft has proven its worth in the
wildfire theatre of operations, due to its speed, flight duration ( 5 Hours ), Range (1,200 Miles ) and ability
to carry a good fire retardent load of 760 US gallons, the A-26 Invader became the mainstay in the battle to deal with the
ever growing problem of forrest fires in both Canada and the United States, with some 45-50 A-26 Invader's being converted
for Air tanker or drop planes of some or other description.
And to prove the durability of the A-26, N5457V as mentioned above still
flies today, owned and operated by David R. Lane.
The first Invaders used for Air Tanker duties comprised of
modifications consisting of systems and componants from a variety of othe aircraft of that era.
The basic conversion consisted of installing an aluminum tank
with two internal compartments, each having the capacity of 500 + gallons of slurry and their own doors in the bombay, an
electrically powered hydraulic system, which was the tail turret hydraulic system removed from a PB4Y-2 and the associated
wiring, tubing and controls to operate the tank doors.
In most of the aircraft, the hydraulic panel was located on
the starboard side of the cockpit, with the jumpseat removed and which was eventually replaced with a lap belt so a passenger
could be carried when required. Just aft of the mainspar, a 1 ft x 3 ft rectangular hole was cut on top of the fuselage for
tank venting.
The windbreaking strakes which were mounted just forward of
the bombay were removed and in most cases, the opening was not covered. The tanks fitted snuggly in the bombay and extended
2 or 3 inches below the bombay.
The most noticable difference was in the bottom of the tank.
On some tanks, the bottom was flat from side to side, while on others the center line of the tank would be 3 or 4 inches lower
than the sides creating a splayed V when viewed from the front.
The list below gives just some of the companies that
used the A/B-26 for various Air Tanker and Agricultural spraying duties.
Photos for several of the companies are not available, so a
brief history has been inserted whilst a suitable image can be located.
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Fleet
grounding In the United States, most of these
aircraft are privately owned and contracted to government agencies, and the National Guard and the U.S. Marines also maintain
fleets of firefighting aircraft. On May 10, 2004, The U.S. Forest Service (USFS) and the Bureau of Land Management (BLM) suddenly
announced that they were cancelling contracts with operators of 33 heavy airtankers. They cited liability concerns and an
inability to safely manage the fleet after the crashes of a C-130A Hercules in California and a PB4Y-2 in Colorado during
the summer of 2002. Both aged aircraft broke up in flight due to catastrophic fatigue cracks at the wing roots, so sadly as
a result of the new legislation no A-26's currently fly in an air tanker capacity.
 
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