By Vic Syracuse, EAA Lifetime 180848
This piece originally ran in Vic’s Checkpoints column in the March 2024 issue of EAA Sport Aviation magazine.
When it comes to test flying any aircraft, I think it is important to review the emergency procedures for any possible scenario before the flight. This is a practice that I have always maintained, and I have found it especially important as I’ve progressed through the flight testing of the Hummingbird helicopter.
Perhaps my focus is better with regard to the Hummingbird since I am a low-time helicopter pilot, but I’m also reminded during every preflight how much more complicated a helicopter is than an airplane. There are certainly a whole lot more moving parts on the helicopter. Truth be told, I am probably the weakest link. But that doesn’t mean I shouldn’t be prepared. It’s all about reducing the risk to both the aircraft and the occupants.
I recently found that my approach worked in my favor. One of the important procedures that helicopter pilots need to be proficient with is the autorotation characteristics of the helicopter they are flying. The Hummingbird setup and maintenance manuals are very good in this aspect. Even though you initially rig the blade angles for a specific low pitch, high pitch, and range of motion, there are required flight tests in which you more precisely track the blades and ensure that there is enough low pitch in the blades for an autorotation.
For those who don’t know, an autorotation is the maneuver that is performed if the engine were to fail while in flight. For this discussion, I am going to be referring to the autorotation performed after an engine failure in forward flight at more than 500 feet over the ground. It is of utmost importance after an engine failure to maintain the rotor rpm during the descent so there is enough energy left to flare at the bottom before touchdown.
I had been doing a lot of autorotations lately and making small corrections to the main rotor blade angles to achieve the specification in the manual. Specifically, with a full down collective and 50 knots of airspeed, the rotor rpm should stay in the range of 310-340, which is the green arc on the gauge. There is some allowable range on either side of those numbers for different speeds and weights. My initial entry into the autorotation maneuver showed the rpm deteriorating below the green arc, which made me uncomfortable. I spent some time rerigging the pitch control system to achieve a flatter pitch.
I do want to caution any of you who may be building your own helicopter. All helicopters need to have their rotor systems set up correctly for autorotation. I remember my flight instructor telling me to not do any autos without an instructor on board. That was ringing loudly in my ears as I approached this phase of testing. However, I had done a couple of in-flight autos with Alex Anduze in the factory helicopter a little more than a year ago and found them to be gentle and straightforward. Plus, there just weren’t any instructors around here who knew the Hummingbird. So I felt that I could safely accomplish it solo with the right attitude and approach.
All the FAA data points to full touchdown autos as being risky, with a high accident rate. In fact, you need to do a full down auto only on the flight instructor ride. All other auto training is accomplished by recovering to a hover above the ground. I experienced a full touchdown auto only once in an R44 as a demo, and the touchdown was rather rough. I really didn’t care to perform that in my Hummingbird.
On this event I am going to share with you, I refreshed myself again by reading the flight manual for the proper actions to be taken for an autorotation prior to the flight. I noted that the ground temps were perfect standard day temps for the airport altitude, which told me I should be able to come close to the specifications. I even installed the GoPro so I would have a cockpit record to review after the flights.
Startup, rotor engagement, hover, and climb-out were normal in all aspects. My standard profile for this test was to enter the autorotation between 50 and 60 knots at 1,500 feet over the ground, lined up with the runway and close enough to it such that an engine failure would still ensure the runway being made. It’s about eliminating as much of the risk as possible. In this case, it all paid off.
The entry into the autorotation was normal, with the lowering of the collective allowing the needles to split, meaning the engine was no longer connected to the main transmission through the clutch. The correlator on the collective also decreases the throttle as the collective is lowered.
My focus was now out the window as I set up for the descent and kept the helicopter aligned with the centerline. During the autorotation there are three things to which one pays attention: rotor speed, trim, and airspeed. It’s a mantra that goes round and round in your head almost all the way down.
During one of my initial glances at the rotor rpm gauge, I noticed the needle with the big “E” on it was sitting at zero. That was the engine rpm needle, and it looked totally out of place. In fact, I had never seen it in that position before other than when the engine wasn’t running. As my mind was processing that thought, I got a “CHECK OIL PRESSURE” audio alarm in my headset. Well, that’s like a hammer hitting your big toe. I did twist the throttle on the collective, but the needle didn’t move. This was now a for-real full autorotation, totally unexpected, but briefed and prepared for.
Quite candidly, it felt no different than the other couple of dozen autos I had been doing over the last few weeks, but I knew things could be way different at the bottom. The descent rate was about 1,400 feet per minute, so I had less than a minute to think about everything and keep my act together to have a good outcome at the bottom. Yes, the mantra “rotor, trim, and airspeed” was loudly playing in my head, along with me telling myself to not screw up. This was for real. By the way, I decided there was no way I was going to take my hands off the cyclic or collective to try an engine restart. The focus needed to be on flying.
I think the preparations and practice over the last few weeks paid off, as well as refreshing myself on the Hummingbird flight manual prior to the flight. All my other training had been done on skid-equipped helicopters. The Hummingbird has wheels, and there is a note that it should be rolled on at 25 knots for an autorotation if terrain permits. I may have been a little faster than I needed to be during the descent, but the Hummingbird can autorotate at speeds from 45-90 knots. It all worked out wonderfully.
I thoroughly checked the helicopter and could find nothing wrong. I could not duplicate the engine failure, so I decided to immediately get back on the horse and do it again. The GoPro showed the second auto to be picture perfect. I’ve done about a dozen more since then, and I’m confident in both the machine and me now. My plan is to certainly stay proficient in autorotation procedures.
As for the engine quitting, I’m pretty sure I may have caused it. The previous day, I adjusted the mixture on the fuel servo as it seemed too lean. I’ve since gone back and readjusted the mixture, as I set it too rich. It’s a fine adjustment. I’ve also wired a START function to the cyclic stick. That way I will never need it again.
My advice to all of you doing flight testing of your aircraft: Plan for the unexpected and you will be ready for it. Eliminate as much of the risk as possible and stay proficient. It will keep the fun factor alive.
(For those of you who wish to watch the entire sequence, view the link at EAA.org/Extras.)
Vic Syracuse, EAA Lifetime 180848, is a commercial pilot, A&P/IA mechanic, designated airworthiness representative, and EAA flight advisor and technical counselor. He has built 11 aircraft and has logged more than 10,000 hours in 74 different types. Vic founded Base Leg Aviation, has authored books on maintenance and prebuy inspections, and posts videos weekly on his YouTube channel. He also volunteers as a Young Eagles pilot.