One of the joys of flying helicopters over the ocean is that one’s flight time can be extended indefinitely. Well not indefinitely becasue at some point one has to land, shut down and grease the main and tail rotors. You can pick up food via the hoist and we had relief tubes. For Number 2, there was a different process that we shan’t get into for the faint of heart.
The only thing that one can’t do while flying or hovering is grease the tail and main rotors. Theoretically, one could land an H-3 in the water, shut down the rotors and ask a crew member grease the rotor head and then shimmy out the tail pylon and grease the tail rotor. This is not recommended for many reasons. The H-3 like many helicopters are top heavy and with the rotors turning, one can easily keep it upright. Shut them down and there is a high likelihood that the machine will capsize. If it does, one will get to spend time in a raft, assuming one got it out!
How much fuel that was on board the helicopter was the primary limiting factor. In the Navy, jet fuel is called JP-5 and each gallon weighs 6.8 pounds.
The H-3 carried 4,500 pounds (662 gallons) of the stuff. Some models could carry two external tanks on the forward ordnance stations that added another 750 pounds (110 gallons) of fuel. There were even SH-3Ds that had an extra internal “donut tank” around the hole through which the sonar dome passed that held another 1,000 pounds (147 gallons).*
Theoretically, in a D model, we could take off with 6,500 pounds of fuel internally and another 1,500 pounds externally for a grand total of 8,000 pounds. With this amount of fuel, the SH-3D could fly about eight hours!
As a practical matter, we normally took off with 4,500 pounds which was good enough for 4.5 hours, light off to engine flame out. I’ve flown an A and a G with the external tanks full and sometimes in the D’s we took off with 6,000 pounds or about six hours of fuel.
In flight at 90 – 110 knots, the rule of thumb number for fuel consumption was about 1,000 pounds an hour. In a forty foot hover with about 3,500 pounds of fuel on board, the two engines burned about 1,400 pounds per hour. Yeah, yeah, I know temperature and humidity have a lot to do with the actual fuel burn rates but more about that in another note of From the HAC’s Seat.
Often we would be asked to extend our time on station or fly somewhere that would require more fuel we had on board. When we were asked to stay out longer, we would take on fuel from a destroyer someplace in the vicinity of where we were or enroute to the new location.
Landing a helicopter on a the helo deck of a destroyer or cruiser usually means the captain has to turn the ship so the wind was either coming over the helo deck 30 degrees from the port or starboard side. This is easier asked than done in a tactical situation.
If we were chasing a submarine, the destroyer had its towed array out and this wasn’t possible because turning would change his sensor picture. How and why is well beyond the scope of this post.
And, because we’d “up dome” at the last possible minute, we’d often arrive at our potential source of fuel with the low fuel warning lights staring us in the face. The yellow light suggested we had at most 20 minutes of fuel left. FYI, the fuel totalizer systems, a.k.a. the gas gauges in both the H-2 and H-3 weren’t accurate at low fuel levels and the low fuel lights were a separate system. One cross checked the two and believed the lower number in terms of flight time.
The process of refueling from a non-aviation ship, i.e. a destroyer or supply ship without landing in the U.S. Navy is called HIFR. The acronym stands for Helicopter Inflight Refueling and most, if not all Allied navies it. I’ve taken on fuel from Australian, British, Canadian, Japanese, Dutch and Norwegian ships.
To HIFR, the helicopter lowers the hook at the end of the hoist and a sailor connects hose nozzle. The hose is pulled on board the helicopter as it slides off to a position about 20 feet from the side of the ship and about 40 feet off the water. In essence, the helicopter is flying formation with the ship at anywhere from just a few knots to 10 – 15 or more.
With the nozzle on board, the aircrewman takes a fuel sample in a large glass jar. If the fuel is clean, he then connects the hose nozzle to the receptacle and signals the ship to start pumping. If all goes right, in about five to 10 minutes, the helicopter has full internal tanks. The crewman disconnects the nozzle from the receptacle and the pilot flying slides back over the helo deck and the hose is lowered via the hoist.
Day or night, HIFR’ng is a relatively routine procedure. The pucker factor increases when the fuel sample wasn’t clean.
The first step was to take a second sample. If you arrived with the low fuel warning lights burning brightly, time was of the essence. Just to get into a hover, pick up the hose and take a sample takes five to seven minutes. If, the low fuel lights tell you that you only have 20 minutes of gas left, the pucker factor in the cockpit is rising with each passing minute. If one has to ditch, one wants to do it with the engines running!
It now is decision time. One choice, take on the “bad” gas and hope the debris doesn’t clog the helicopter’s fuel filters and shut down the engines which will force the helicopter to ditch. Choice two, ditch now before running out of fuel.
All the environmentalists will cringe when they read this. When we had “bad” samples, the air crewman would hold the nozzle over the side of the helicopter and squeeze the handle and pump out fuel for 20 – 30 seconds before he took a second sample. If it was clean, great. If not, we’re back to the decision as to whether or not we should take on bad fuel.
So why was there a chance of bad fuel? Well back in the old days when U.S. Navy ships burned a heavy black oil known as Navy Distillate #2, JP-5 was stored in separate tanks. And one of the oddities about JP-5 is that algae develops in the fuel when it is stored in a dark place and not mixed frequently. Bridge watches were briefed to stir the JP-5 tanks periodically. If a ship didn’t do this for a few days, the algae began to grow. After a week, there’s algae in the fuel. To clean the algae out, the ship has to empty the tank and flush it out with chemicals that kill the algae.
However, the younger generation has benefited because all the non-nuclear ships now use JP-5 as fuel. So what we take on from a ship during HIFR is the same fuel the ship burns and they keep it stirred. Problem solved.
As an HAC, I’ve HIFR’d hundreds of times. Ninety-nine percent of the time the fuel was clean. When the sample is bad, usually it is at night and in bad weather when we were really low on fuel. Looking back at those times, bad fuel samples and low fuel states just added to the fun and excitement.
* Data is taken from my SH-3D NATOPS dated 15 October 1974 with changes up to #41 and from my SH-3A/G/HH-3A/UH-3A NATOPS dated 1 July 1974 with changes up to number 65.