Robinson R66

a preview-turned-review by Philip Greenspun, ATP, CFI-H; updated April 2017

Site Home : Flying : One Article

I wrote this in 2009 and 2010, before the October 2010 certification of the R66. I've updated it with some information learned during the Robinson Factory Safety Course in 2013 (I did the R66 version) and also while flying with local owners of the R66.

The Robinson R66 is a five-seat turbine-powered helicopter with a two-blade teetering rotor system. It should be certified by the end of 2010 [it was!], with customer deliveries in 2011 [it happened in November 2010]. With a few instruments in the panel, a GPS, and an ELT, the helicopter will cost about $800,000 [$910,000 in 2017]. Robinson has provided no price, weight, or date for the availability of air conditioning, though it can be ordered. [$23,500 and 43 lbs. on the 2017 price list]

The Robinson R66 offers two comfortable front seats separated by a central cyclic control, the famous Robinson "T-bar" design. The back seat is just barely wide enough for three passengers and has enough legroom for a passenger up to perhaps 5'4" in height. The machine offers cargo space underneath the seats and in a spacious (18 cubic foot) rear cargo compartment.

Engine controls are mechanical, with no FADEC to prevent hot starts, hung starts, or overtorquing, any of which can be caused by a student, low-time, or distracted pilot and all of which can easily cost $50,000 to inspect and repair. Flight instruments are mechanical, the traditional 6-pack of steam gauges. No autopilot is available.

This article was based on the author's February 2009 visit to the Robinson factory and inspection of a flying R66 and on pricing and performance announcements in February 2010.


Bell Helicopter at one time made more helicopters than any other company in the world, primarily on the strength of the B206 JetRanger. Frank Robinson introduced the two-seat R22 in the late 1970s and it was noteworthy for being very fast while offering the lowest operating costs of any helicopter. Bell said " We don't have to worry about this cutting into JetRanger sales; he will never make a four- or five-seat helicopter." Frank Robinson introduced the four-seat R44 in the early 1990s. The R44 came very close to a lot of JetRanger numbers in terms of payload and cruise speed, at an acquisition cost of one quarter that of the JetRanger and an operating cost of less than half. By limiting the power drawn from the piston engine, the power plant/tranmission reliability of the R44 has been very close to that of small turbine-powered helicopters.

Faced with a decline in JetRanger sales due to the R44, Bell must have been thinking "We don't have to worry because there are some customers who demand a jet engine and there are some customers who need five total seats. Robinson will never make a jet-powered or five-seat helicopter."

In March 2007, Frank Robinson announced the Robinson R66, a jet-powered five-seat helicopter. In January 2008, Bell Helicopter announced that it was ceasing production of the JetRanger. [In 2013, Bell announced what became the 505 Jet Ranger, which limped into production in 2017.]


According to a February 9, 2010 Robinson press release, the R66 will have the following weight and performance specifications:



Loaded up with a few gyros and a Garmin 430, the R66 has a remarkable full-fuel payload of just over 900 lbs. If America gets any more obese, this will be an incredibly popular helicopter. This compares to about 650 lbs. for the R44 Raven I and 700 lbs. for the Raven II. The range of the R66 is about 50 n.m. less than the more fuel-efficient R44s, which can go roughly 375 n.m. on their 50 gallon tanks, compared to 325 n.m. for 74 gallons with the R66. Of course, you could get two R44s for the price of one R66 (three or four if the R44s were purchased used), so the payload per dollar is better on the R44. Also, the best comparison would be to an R44 that had been fueled only to the same range as the R66. In that case, the Raven I payload is more like 700 lbs. and the Raven II is about 725 lbs.

Cruise speed on the R66 is only about 5 knots faster than the R44. The high altitude performance should be much better, though, on the R66.

One thing that delayed the R66's certification is a weakness in the traditional Robinson tail rotor design. The tail rotor was already stressed enough when the helicopter was flown in a slip that Robinson had to put out a Safety Notice admonishing pilots not to fly the R44 out of trim. When the tail rotor was scaled up for the R66 the weakness became even more pronounced. Rather than hinder law enforcement and TV station usage with a limitation against flying out of trim, Robinson redesigned the tail rotor. So if you need to fly sideways all the time, the R66 could be much more useful than an R44.


The Robinson R66 is unlikely to be inherently safer or offer more powerplant/transmission reliability than the R44. Turbine engines have a reputation for extreme reliability, but physically small turbines, such as those that go into low-power helicopter engines, are subject to a lot of thermal stress and are not nearly as reliable as the turbines in an Airbus. Piston engines have a reputation for unreliability, but that was earned when the engines were operated at 100 percent power. The R44 is a demonstration of the most reliability that you could ever get from a piston engine; the Robinson R66 and similar light turbine helicopters demonstrate the least reliability that you could ever get from a turbine engine, especially when you factor in the need for a very sophisticated transmission (turbines spin at up to 50,000 RPM; helicopter rotors spin at around 400 RPM).

Robinson developed a big safety edge over other light helicopter manufacturers when it began shipping factory-installed HeliSAS autopilots in 2015. When operating single-pilot, everything from an inadvertent encounter with IMC to a simple need to reprogram the GPS flight plan will be a lot safer than in a helicopter with no autopilot.

The Engine

What I wrote in 2009: Back in 2007, Robinson and Rolls-Royce announced that the R66 would use the RR300, a modern somewhat simplified derivative of the Allison engine that has powered thousands of JetRangers. Rolls-Royce says that Full Authority Digital Engine Control (FADEC) will be a customer-specified option. Frank Robinson never met a computer chip that he thought could do a better job than a nervous 20-hour student pilot, so my guess was that the R66 will ship with a manual engine control system, just like a 1962 JetRanger. As a practical matter, that means hot starts ($50,000+) and in-flight distractions resulting in overtorquing and overtemping. Considering how many students overspeed the R22 and R44 in training, and the expense of inspecting an abused turbine engine, the lack of a FADEC would preclude the R66 as a civilian primary trainer. My suspicion was confirmed in February 2009 when Frank delivered a talk at Heli-Expo saying that the R66 would have old-school mechanical engine controls.

The RR300 in the R66 will supposedly be rated at 300 hp for takeoff, 240 hp max continuous, and 220 hp in cruise flight. This compares to 420 hp takeoff power in a modern JetRanger and 245hp takeoff and 205hp max continuous in the R44 Raven II.

The new "Rolls Royce" engine is in fact, from a type certificate point of view, the same old Allison Jet Ranger engine. Thus the manufacturer skipped out on all of the new rules. It is mounted in an unusual position: behind the rear passenger seats rather than on top of the helicopter as is conventional for light turbines.

A big advantage of the mounting location seems to be reduced cabin noise compared to, e.g., the Bell 505.

Disadvantages of the mounting location: soot from the exhaust tends to coat the underside of the tail (don't order a ship with a white tail!); the exhaust is low enough that a 4-year-old child could drop a marble straight down into the power blades ($50,000 in maintenance after the next start!).

Prior to certification I wrote that the lack of a FADEC combined would likely lead to hot starts. At the 2013 safety course I learned that roughly 2 percent of R66 engines had already been blown up by owners and pilots. Robinson created a user interface hazard by lifting the old mixture control from a R44 to serve as the fuel cutoff lever. It is a continuous lever instead of ON/OFF as with a typical turbine "condition lever." So owners have been failing to pull it all the way back during shutdown. Then they go to start it up and a bit of fuel is constantly seeping into the burner area. When the thing finally does light off there is a huge explosion and they need to buy a $250,000 new engine (minimum cost to fix $80,000 according to Tim Tucker). The start button and mixture control are in the same positions as on an R44 Raven II. So if you rely on your muscle memory to start an R66, using the same motions as for a Raven II, boom! You introduced fuel before the engine reached 15 percent and now it will be $80,000.

A computer silently records any exceedances so that you can spend $100,000 on engine teardown at your next annual inspection. However, the same computer isn't wired into the audio panel to warn you when you're exceeding, or about to exceed, a limit. This is kind of the worst of all possible uses of electronics. My letter to friends from the safety course: "no advances in electronics are incorporated; you're supposed to do a power assurance check every day where you fly around while looking at tiny placard to figure out if the engine temperature is as expected given torque and altitude. Why isn't a $2 microcontroller doing this? We know the answer for the Jet Ranger (it was certified before the microprocessor existed) but why can't this fancy new Rolls Royce engine do it?"

One of our instructors responded to this with "Are you considering purchasing an R66?" and I replied "I'm a lot less interested now that I see that the pilot workload has been increased (if nothing else now monitor two gauges (temp and torque) instead of one (manifold pressure)) and therefore it would be impossible to rent the ship."

An owner's perspective: "Here at sea level it is always the torque that is limiting. You have to constantly watch the gauge to make sure you're not over 83 percent. It isn't like a Eurocopter that will beep at you when you're into a 5-minute zone."

Interior Noise

Cabin noise in a 2012 Robinson R66 with 1135 hours on the clock was measured with a $200 Extech meter. All numbers are in dBA and the two measurements are for measurements taken near the front seat occupants' ears and near the back seaters' ears. For front seat occupants, this is 4-5 dBA quieter than a Bell 505. That's like going from a Corvette to a family sedan. The back-seat ride is about 2 dBA quieter than on the Jet Ranger 505.

Loafing at 90 knots, this is 4 DBA quieter than an R44. At 110 knots, nearly 3 dBA quieter for the front-seaters.

If you care about interior noise level, consider air conditioning to be a mandatory option. Ripping along at 120 knots, fully opening the vent adds an insane 6 dBA to the noise level in the front seats. Opening it half way adds closer to 2 dBA. At 90 knots the vent still adds 5 dBA. You have to really want to be cool.

How good is 87 dBA at 110 knots (about as fast as most people are likely to cruise in real-world situations)? "Sikorsky has measured the noise levels of the D model at 86 dBA externally and 83 dBA internally, compared with 92 dBA and 87 dBA, respectively, for the C series." (Aviation Week). The R66 is therefore as quiet as an $8 million executive transport helicopter (though Sikorsky's latest version is substantially quieter and there may have bee a "super soundproofed" version of the S-76C that was quieter).

Compared to the R44

The Robinson R66 bears a strong physical resemblance to the R44. Instead of a cooling fan in the back, there is a small turbine engine and a big exhaust pipe. The space formerly occupied by the piston engine is now a baggage compartment, big enough for a few full-size suitcases and accessed via a single door on the passenger side. The R44 has reasonable baggage capacity underneath the four seats, but no compartment is large enough for a set of golf clubs, for example. The back seat of the R66 has the same amount of legroom as an R44 (i.e., not much), but is slightly wider and therefore can theoretically seat three people.

The Robinson R66 might be more profitable for medium-volume sightseeing operations, assuming that the rides are short and passengers can tolerate being crammed into the back seat. Customers tend to arrive in groups of two, so having four passenger seats rather than three will be a help.

Many foreign militaries use the R44 as a primary trainer. The U.S. Army uses the JetRanger because (1) taxpayer money is free, and (2) they want army pilots to have turbine startup and shutdown experience from Day 1. The R66 probably won't win over the U.S. Army, but it should be hugely popular with foreign armies. [Update: for primary training, the U.S. Army switched from its $600/hour Jet Rangers to $5,000/hour twin-engine Eurocopter EC145s. See "U.S. military saves taxpayer dollars by replacing $300,000 helicopters with $6 million ones".]

Compared to a new Bell 505 Jet Ranger

Please see our separate review of the Bell 505.

The big picture:

Compared to a Eurocopter EC120

The Eurocopter EC120 is a lovely five-seat machine with a fenestron (shrouded) anti-torque rotor in the tail. A 10-year-old EC120 sells for about $900,000. Due to the conventional tail rotor and less paranoia about waking up the neighbors, the Robinson R66 will be substantially noisier than the EC120, whose flyover noise is 3 dB quieter than the R44 (FAA Advisory Circular AC36-1H). It will also have more tail rotor authority.

The EC120 has a smooth three-blade rotor system that is always going to be more comfortable at higher airspeeds than a two-blade Robinson or Jet Ranger rotor. The EC120 has fancy glass engine parameter displays, but no FADEC. An experienced EC120 pilot had this to say

"The EC120's start up is all pilot-controlled. The EC120 is very easy to hot start, as one needs to manipulate the throttle somewhat and the thumb is holding the start/cranker in position, so it is tough to fine tune the throttle at the same time."
The EC120 has a variety of glass cockpit and autopilot options; Robinson is going to deliver the R66 with a 1950-style six-pack of steam gauges.

The EC120, like other traditional turbine helicopters, has a very large and comfortable back seat, making it a credible machine for executive transport. The EC120 is a vastly better ship for photo enthusiasts, with a large sliding photo window in front and a rear door that slides completely open or closed in flight. With a Robinson R66 you would need to do any photo mission with a door removed entirely, not very practical in cold climates.

The Robinson R66 should be substantially cheaper to buy and operate than a new EC120. Eurocopter has developed a bad reputation for service and support. After any initial teething problems are resolved, the R66 should spend more of its time in the air and less in the maintenance hangar waiting for service bulletins and airworthiness directives to be performed.

In a December 2007 survey by Rotor and Wing, Robinson earned the #1 spot for customer satisfaction. Eurocopter was near the bottom.

Compared to an old JetRanger

A new Robinson R66 is likely to sell for the same price as a 10-year-old Bell 206 JetRanger, which first flew in 1962. The aircraft are powered by very similar engines, from the same original Allison design, and should perform similarly. Maintenance, overhaul, and spare parts costs for the JetRanger should be substantially higher, particularly if Bell elects to raise parts prices on the 206 in order to encourage customers to buy its newer 407 design. This is what happened with the Bell 47, the old piston-engine M*A*S*H helicopter. Spare parts got so expensive that it became cheaper for customers to operate the jet-powered 206.

The Jet Ranger and Long Ranger helicopters have much bigger and more comfortable back seats than the Robinson R66. The Bell helicopters also have useful sliding photo windows.

Before the Collapse of 2008-?, an airworthy 1970s JetRanger could be purchased for $250,000, with a pristine example going for closer to $500,000. The most popular civilian helicopter ever made, with over 7,000 manufactured, the huge fleet of used B206s available is the strongest competition to any new five-seat jet-powered helicopter.

Compared to the Sikorsky S-434

In late 2007, Schweizer, a subsidiary of Sikorsky, announced a derivative of their three-seat Schweizer 333 helicopter. The new machine, dubbed 434, has a four-blade rotor system derived from a remotely piloted military helicopter. This could be a very nimble helicopter to fly and has already been sold to Saudi Arabia for use in military training. Seating is provided for three people in a training configuration or four in "utility". Without a fifth seat or a cargo compartment, it is tough to see how the S-434 will compete with the Robinson R66. Given how fat Sikorsky gets on its military contracts, it is tough to imagine them investing the effort to develop a competitor to Robinson's personal helicopter line.

At Heli-Expo 2009, Sikorsky announced that the S-434 had first flown on December 18, 2008. Certification is expected in 2010 with customer deliveries in 2011. The price is approximately $1 million.


Here was my wishlist from 2009...


The R44 is a great two-person helicopter, with the cramped rear seats treated as a cargo shelf. With only two people on board, the machine has a huge amount of reserve power from its simple piston engine. The R44's lack of rear-seat legroom precludes its use as an executive transport. The proximity of the cyclic to a front-seat passenger makes the R44 a little worrisome for short sightseeing tours where there is not a lot of time to brief passengers on the importance of not knocking the control. For most customers, therefore, the R44 ends up being flown most of the time with only one or two people in its four seats.

What do you get by stepping up to the R66? The same lack of rear-seat legroom. The same T-bar cyclic right next to a front-seat passenger. Additional cargo space for bulky items. Is it a true five-seater? Absolutely... if all of your friends are 5'4" tall. Otherwise, it is a two-seat helicopter with a cargo shelf, same as the R44.

The R66 will be substantially more useful than the R44 in some foreign countries or on oil platforms where Avgas is difficult to obtain (though note that the R44 Raven I can run on super unleaded car gas). The R66 may be useful to oil rig operators who want an inexpensive Jet-A-fueled machine for ferrying out packages and parts, a job currently performed by ancient JetRangers. The R66's max-fuel payload of 900 lbs will make it substantially more useful than the R44 for hauling cargo.

For executive transport or sightseeing operators, the R66 would have to be priced substantially cheaper than a used EC120 in order to be attractive.

[2017 Update: Robinson has delivered roughly 800 R66 helicopters, surpassing the number of EC120s built since its 1998 introduction. Apparently a lot of people think the R66 is worth close to $1 million.]


Text and photos Copyright 2008-10 Philip Greenspun.

Reader's Comments

I am surprised about your negative views on the back seat of the R44; I don't think it is as bad as you describe at all. I have spent some time in the back and find it plenty comfortable enough for my 6'4", bulky frame. I'd be more than happy to spend an hour or two flying somewhere seated in the back.

Most of my R44 time (probably 4 hours and counting) has been in the front-left seat. There one design flaw becomes painfully obvious: with the vent lever locked open, the little t-bar sticks out and pokes me in the leg when my feet on the pedals. (not that they ever are, of course; that would be illegal.) So leave it unlocked and re-open it every few minutes is the solution.

-- Bas Scheffers, March 10, 2010

Fast forward to 2013 and Eurocopter has closed the customer satisfaction gap to Robinson to be almost equally good (or bad).

Rotor & Wing OEM Excellence Ratings 2013

-- Andy Course, February 8, 2015

Add a comment | Add a link