Dumping retardant in an emergency

Unless there are firefighters and other individuals on the ground that might be in danger from falling retardant, a tanker pilot can jettison their entire retardant load if in the event of an emergency such as an engine failure or an encounter with bad winds. Typically the pilots will jettison the retardant in a controlled matter to avoid sudden pitch-up of the nose of the tanker. The hope is that once the retardant is jettisoned, the crew of the tanker in trouble can make it safely back to the nearest tanker base.

From what I understand, most if not all tanker bases have a designated area near the base for jettisoning retardant. These jettison areas are important when something goes wrong with the tanker during or after take-off. Most tankers can not land with a full load of retardant, so the pilot will jettison the retardant in the designated jettison area before returning to base to have their tanker repaired.

I promised you some numbers for the weight of load of retardant for a couple of air tankers. If memory serves, one gallon of water weighs about 8.35 gallons. Retardant weighs a little more than 9 pounds per gallon (ppg).

I will talk about three tankers: a DC-7 tanker, a P-2V tanker, and CAL FIRE's S--2T tanker.

Some of you may recall that I wrote extensively about Butler's T-62, a DC-tanker that has been piloted by Larry Kraus for over 27 years. Larry was very generous with his time and his knowledge of the tanker business, so it was easy for me to find information from my blog about weight specifications of T-62 that may found here.

The DC-7 tankers, including T-62, carry 3,000 gallons of retardant. Multiply this by 9 ppg and we can see that the weight of a full load of retardant on T-62 is roughly 27,000 pounds. Larry told me the normal take-off weight of T-62 with a full load of retardant is 108,000 pounds.

The maximum gross weight of a P-2V, for example those operated by Neptune Aviation is 80,000 pounds. While the P-2 can carry about 2,700 gallons of retardant, the current contract load according to Neptune Aviation is 2,082 gallons. 2,082 gallons of retardant comes in at a total weight of 18,738 pounds.

According to CAL FIRE, the S-2T tanker has a maximum gross weight of 29,150 pounds, carrying 1,200 gallons of retardant which weighs a total of 10,800 pounds.

The example of these three tankers, demonstrate how much lighter the tanker is with empty retardant tanks.

I am glad to post this tonight, prior to our latest round of winter. I may have more to say about this subject, but that may have to wait for a bit. In the meantime, enjoy!