Estimated reading time 7 minutes, 39 seconds.
The U.S. Federal Aviation Administration has approved the pop-out floats for the R66 Turbine. Robinson Helicopter Photo
Robinson Helicopter Co. has announced that the FAA has approved the pop-out floats for the R66 Turbine on Nov. 15. Dubbed the R66 Turbine Marine, this new variant of the R66 is similar to the float version of the R44 — the Clipper.
Earlier this year, I had the opportunity to fly the float certification flight test R66 and do an inflight deployment of the floats. Frankly, it was quite mundane. Activation is initiated by squeezing a lever on the pilot’s collective. The deployment came with an audible “pop” and within 2 to 3 seconds, the floats were fully deployed.
There was no tendency that I could detect for the aircraft to pitch — or roll for that matter — during deployment. The only thing I noticed in that time frame was the cyclic stick did a little “stick stir” for one revolution. It was small in displacement and very quick to end.
Just prior to the float ship test flight, I was out doing autos in a stock R66. And the autos in the R66 with the floats deployed seemed about the same. Sometimes I think we look for differences because we believe we should find them. I didn’t do any water touchdowns. They only have salt water near the plant and there is a very detailed and time consuming process to clean the aircraft after it has hit the salt water. I was told it’s like landing in Jell-O — that you can hardly tell you’ve even touched down.
I can believe it, because on the touchdown auto with the floats deployed, I felt like the flare and touchdown were even better than a standard R66, it that’s even possible. Maybe I was just looking for a difference and imagined it to be there. But it did feel a bit easier and softer. Certainly it’s no more difficult and with nothing special to do regarding technique.
The fact that the R66 Turbine Marine was so simple to operate doesn’t mean the certification was simple to obtain. Reasonable thought might be that since Robinson already ran the process with the R44, it should be a no-brainer for the R66. Wrong answer.
First, since the R44 float certification, the FAA has raised its requirements and the margins are even more stringent. The approval process requires that everything is checked. The report handed over to the FAA was 500 pages.
Critical items included proving that none of the standard R66 flight characteristics were altered by the addition of the floats. Hover tests were done at 7,000 feet DA with and without floats. And in-flight strain measurements were required.
Whereas the R44 float inflation helium bottle is located in the left front seat compartment, in the R66, it’s in the right rear seat compartment. With the R66 seats having been certified to newer standards, part of the certification was to show that the deeper crush barrier under the seat cushion would not touch the bottle in a vertical crash.
Besides the blatantly obvious float bags on the skids, another external change is the larger horizontal flat plate at the bottom of the vertical stabilizer. It is twice the area of the standard plate. The plate was required on the original R66 to help prevent nose pitch-up during an autorotation — caused by the larger cabin area. With the float installation, even more plate was required. It sure worked well in my test.
The R66 Turbine Marine is similar to the float version of the R44, known as the Clipper. Robinson Helicopter Photo
What hasn’t changed from the R44 are the floats themselves, with six chambers per bag. The packed floats present the same low profile as in the R44 Clipper, making them easy to step over when entering and exiting the helicopter. Certification requires that the aircraft must be stable in the water with one of the twelve chambers inoperable. Vne with the floats deployed is 80 knots.
For emergency use, the floats must be able to provide floatation with a 25 percent excess buoyancy rating. This means that for the R44 Raven I, which has a 2,400-pound gross weight, the emergency floats must provide buoyancy for up to 3,000 pounds.
However, for non-emergency use where the floats are to be considered “main” floats — meaning approved for water takeoffs — they must provide for 60 percent excess buoyancy. So in the case of the R44 Raven I, that ship can take off from the water at 100 percent of gross weight. But for the slightly heavier R44 Raven II, it is restricted to 2,400 pounds for a water takeoff.
In the case of the R66, Robinson set the maximum takeoff weight from the water at 2,200 pounds to help provide more space between the undercarriage of the helicopter and the water. This is certainly enough for two people and decent fuel for training operations. Although I question how many operators are really going to be doing repetitive autos to the water in a million-dollar turbine helicopter.
The R66 Turbine Marine will be sold only as a separate — and specific — helicopter. Field retrofit kits for existing R66 Turbine helicopters will not be available. The floats add 65 pounds and $36,000 to the weight and cost, respectively, to the basic helicopter versus the basic R66 Turbine.
Robinson flight test engineer, Dale Taft, admitted: “The float certification probably could have been done faster. They didn’t get maximum priority push all the time because of the work on the glass panel that was concurrent.” He explained, “Certifying the floats is a well-defined process – you just churn through it. But with the glass panel, it takes so long because of the human factors and working with the FAA to get a common ground. They only have so many people and needed to know what was critical. The avionics certification took 1 and half years.”
Company president, Kurt Robinson told Vertical during my visit to fly the R66 Marine, “Had I known the glass panel process was going to be what it was, I would have done the floats first.” Regardless, the R66 Turbine Marine is here now. And I’m sure this will please many prospective R66 buyers waiting for that over water safety advantage.