Up close and personal with DC-7 tankers: retardant drops pt 2 of 2

In my last post, I was writing about the Aero Union multi-door tank system (8 doors) used by Butler's DC-7's. I'll let Larry explain to you the sequence he goes through making a typical retardant drop:

To drop a full load at Coverage Level 6, I would have the co-pilot arm the tank system, and I would set the intervelometer to the 12 o'clock position (1), set the timer to 0.4 and set the doors to open selector to 8. Assuming that we'd gone through the Descent Check List while descending into the drop pattern I should be set. All that I have to do next is to determine the correct place to begin the drop and hold down the drop button (located on the yoke) until all of the doors open.

I know that there are times when tanker pilots must make an emergency drop of a retardant load. If an emergency happens near a tanker base, there is usually a designated place, e.g. coordinates, where emergency drops can be made. Otherwise, the pilot tries to look for a safe place -- no houses, no people on the ground, away from water sources, etc. -- to make the emergency drop. As I understand it, if a tanker pilot were to drop the entire load at once (aka a salvo) while making an emergency drop, the nose will do a sudden pitch up because of the sudden loss of 27,000 pounds of retardant. Often the pilots have a few hairy moments when this happens as they bring the tanker under control.

In the case of the DC-7, Larry tells me that emergency dump switch (outlined in blue in the photo) is centrally located on the cockpit panel. When Larry or his co-pilot lift the guard and activate the system by flipping the switch to the up position, the doors open at an approximate coverage level 5 drop. If I am thinking about this correctly, an added benefit is that an emergency drop at an approximate coverage level of 5 means that any pitch up of the nose of the tanker will not be nearly as bad as a sudden salvo of all doors at coverage level 8 (or higher). Larry provides some more details on emergency drops:

As far as having to jettison retardant in an emergency, it all depends on the severity of the emergency, the location and other local circumstances. In most cases, such as an engine failure deep in a canyon, there will be time for some quick (maybe 15-30 seconds) of trouble-shooting followed by determining if there is time (and the terrain allows) to fly to a suitable drop area. If we really are deep in a canyon, a suitable drop area will be anyplace nearby that doesn't contain a water source, people, vehicles or structures.

Again, it all depends on the circumstances. Generally, it will be possible to fly a few miles to an open area, but it's better for a spot on the ground to be covered with retardant than the flaming wreckage of an airplane. It would be unlikely that we would climb out of a canyon with 3 engines to carry the load to a designated jettison area. However, if the failure occurred enroute to the fire at altitude, that could be an option. There are also other emergencies not involving engines. Hydraulic problems being high on the list. I also once had a failure causing the loss of the fabric on the rudder on Tanker 62 during a drop run.

As I've mentioned before, nothing is ever easy in the tanker business.