I was finding out that something loose in one place can destroy other things not
necessarily related. Or you just crash.
Text & Photos by Tom Hintz
Posted – 2-4-2014
Last Sunday I took my T-Rex 550E PRO DFC that I have become very comfortable flying and my brand new Align T-REX 700E PRO DFC out to our club field. I was anxious to get the new Align T-REX 700E PRO DFC in the open air of the flying field to see what it was like. The Align T-REX 700E PRO DFC came to my house on Friday morning and I began the build right then. I discovered that I needed a set of solder bullets to get the ESC and motor connected so we went to a local hobby shop where my weekend got a bit more complicated. When I walked in (my first visit to this shop) I immediately noticed an E-Flite Carbon Z Cub that was sold out on all of my favorite on line vendors sitting on the shelf. Naturally I grabbed that along with my bullets.
I actually finished building the Align T-REX 700E PRO DFC early on Saturday afternoon so began assembly of the Cub. Since my work days normally begin around 2 am I had the Cub ready to maiden in time for the Sunday trip to the field.
I took the Cub up first as the wind was calm and I suspect that 85” of foam wing might be easily bounced by the wind and complicate trimming it out. I assembled the wings, set it on the runway and it took off and flew hands off just a few feet above the runway. I put it through some basic maneuvers during that flight and another later in the day. No problems with the Cub so I turned to the Align T-REX 700E PRO DFC next.
The first time lifted the Align T-REX 700E PRO DFC off of the ground it spun hard but I smacked it back down after one rotation and then hit Throttle Hold which I know I should have done first but I wasn’t letting go of any sticks with it spinning like hat just above the ground. When it set down the vertical stab at the end of the tail boom flexed and sheared off the tail rotor blades. We discovered that I had the tail sensor direction reversed in the Spektrum AR7200bx so corrected that. A friend at the field flew his Align T-REX 700 a few times and gave me is tail rotor blades to use.
The second flight started out with just a bit of the tail wanting to swing right. I landed it and added a few clicks of left rudder trim in the BeastX and took off again. This time it started out fine in a hover so I spun it a couple times and the right drift of the tail came back, and then went away as soon as I went to forward flight. I again landed the Align T-REX 700E PRO DFC and raised the gain by 10 points and the tail seemed locked in when I once again took off to complete the flight.
After about 2 minutes of fast forward flight and lots of turns, a couple rolls and loops I was making a banked left turn and the tail boom broke off. Now dramatically shorter the Align T-REX 700E PRO DFC began to spin but I did remember to hit Throttle Hold this time. I was a little surprised that with the motor off I again had some control. This was my first ever attempt at an autorotation so I failed miserably. I did give the Align T-REX 700E PRO DFC full up as it went down behind a small hill but the thump we heard confirmed that I had no up left to give.
The damage was confined to the snapped tail boom, broken landing gear, one DFC arm end snapped off and the elevator servo had stripped its gears. Of course my shiny cowl was cracked and some paint had chipped off but considering the small amount of damage otherwise I would learn to live with the cowl.
Everything in the broken tail boom, gears, torque tube and the rear gear box were perfect. So my failed autorotation may have actually helped some. I would get it repaired and ready to fly a couple days later.
Helicopter landing gear seem to be
expendable.
It appears that while finishing the Align T-REX 700E PRO DFC build I discovered that the locking bolt hole in the tail boom was not perfectly aligned with the hole in the tail boom housing. I loosened the four bolts that clamp the housing around the tail boom, tweaked its position so I could get the locking bolt in place. Apparently I forgot to re tighten the four bolts. That let the tail boom work back and forth in the housing which likely caused the occasional right swing of the tail. Eventually the aluminum boom fatigued and snapped just inside of the housing and the only things holding it to the body was the two support struts which held up and remain in good condition.
I turned to flying my T-Rex 550E PRO DFC and got a couple flights in on that without incident. I was considering going home when I thought one more flight on the T-Rex 550E PRO DFC was in order. A few minutes into that flight is decided to do a back flip and apparently did not have it squared up because when I hit down collective as it flipped it squirted off to the side which surprised me and from that point on I was WAY behind on the sticks. That fight lasted ¾ second or so and ended abruptly when it went into the ground under power, at speed making that sickening “thump” sound. All my fault, probably starting by going into the flip without having the T-Rex 550E PRO DFC level (skids flat to the ground) in the first place.
I was sure I had just killed my T-Rex 550E PRO DFC but would later note the damage was surprisingly light. The main rotor blades were history, one of the tail rotor blades was gone and the other would be trashed, (I don’t fly a blade that has been through that!) the tail boom was bent somewhat, the landing gear were busted up, the main gear had chipped a few teeth off as did the forward tail rotor drive gears. Both of the DFC arms had snapped their plastic ends off but the arms themselves were fine. I know that sounds like a lot of broken parts but if you had witnessed the force with which it hit the ground I think you would also consider the damage to be light. Those who fly this type of helicopter know that my list is nearly all cheap parts with the exception of the main rotor blades.
I think it is safe to say that I flat whiffed going back over the Align T-REX 700E PRO DFC as I normally do to check all of the fasteners one more time before taking it to the field. I try to hover a new (or repaired) helicopter in the yard a few times and then go over the fasteners to see if anything loosened up or a setting changed. Whatever happened I missed tightening four bolts and that caused my brand new Align T-REX 700E PRO DFC to go into the ground. Granted the damage was minimal but it still ticked me off.
If I had not looked closely I may not
have noticed this cracked gearbox.
The T-Rex 550E PRO DFC crash likely came from me starting to feel a little invincible. I had been throwing the T-Rex 550E PRO DFC all over the sky the last few weeks and though I was making mistakes now and then, I was regaining control easily. I had strayed into a false sense of security and I got careless on the sticks. I can do back flips easily when I enter them with some thought. This time however I just did it without thinking it through and the T-Rex 550E PRO DFC paid the price. Here again the damages were minor considering what happened and I am thankful to Align for the durability of their helicopters.
I have since flown my rebuilt T-Rex 550E PRO DFC and all is fine there. The Align T-REX 700E PRO DFC will hopefully fly again this coming weekend. Hopefully I will show both of them more respect. I proved to myself that I am not an instinctive pilot and I have lots to learn about controlling these aircraft, especially in the odd attitudes that I can accidentally get them in. I do not mind working on my helicopters but by paying attention I can limit that work to checking them over between days at the field.
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