Nothing is as simple as we hope it will be. I have crashed my Bergen Gasser and when I analyze the accident chain resulting in the crash, I am amazed at how many opportunities I passed up to prevent it. As such, I have decided to share the story with others, hoping my experience may be helpful in preventing a similar type of needless mishap.
The goal was to bring my Raptor 50v2 (which was ready to fly) and my Bergen Gasser (which needed some minor maintenance) to the field on 12/14/13 because it was the last day of the year when two of my flying buddies would be able to come. From the get-go, there was pressure to complete the repairs and head out to the field. Unfortunately, the time available to carry out the repairs went from over 6 hours down to less than 2, due to other matters not related to model helicopters. I estimated it was plenty of time and started the repairs.
After fixing the known problem, I looked over the machine and found some slop in the tail linkage. My gut feeling was to think it was time to leave that machine behind, but I listened instead to another little voice, the one that said "hurry up and fix the sumbitch!"
I had never replaced any parts in that area, and I had the parts on-hand. Unfortunately, due to hurrying to finish up, unbeknownst to myself, I reassembled the tail with the grips 180 degrees from their normal position!
I would see that if I had taken the time to verify the system entirely. What I did instead is verify there was no binding, and everything was smooth. No excuse. As we say where I'm from, I had lowered my pants and screwed myself.
As I quickly exercised the other servos, I realized I did not care for the sound of the left-right cyclic servo. The more intently I listened to it, the weirder it sounded, and I am not kidding, I saw the servo fail, right there, on the bench! 'Talk about luck!! I always said this machine was blessed, somehow.
Most right-thinking human beings would at this point have called it quits, and left that helicopter home. I thought about doing that. Do not ask me why I decided instead I would hurry up and swap the servo out! All I know is, in a frenzy of tools, and renewed time pressure, there I was, swapping servos, reminding myself how much I dislike working on that machine, which is probably why it needed all that work in the first place
As soon as I was done drilling the servo wheel per the manual, and adjusting the push-rods a smidgen, I checked the battery voltage, and decided to give it a quick charge while I was eating. As soon as I was done eating, I loaded up the truck, forgetting in the process that the helicopter was plugged in the charger! When the wires pulled loose, I stopped, and thought "Jesus! I'm in too much of a hurry!" I swear, I again considered leaving the machine at home; and did not do so...
When I made it to the field, it was very windy. I first flew the Raptor a couple of times, and my friends flew their machines, and then I decided it was time to pull out the Bergen. The day was going great. I asked one of the guys to help me get it started, after I made sure I had fueled it up. I say that because twice in the 9 years I've had this helicopter, I've started it up thinking it was full of fuel, and had to auto it down because it was another helicopter I had refueled a few minutes earlier. This is the first item on the checklist I have taped to my transmitter, before verifying the proper model is selected, and checking the voltages of the batteries on the TX and on the model. That checklist also includes to verify all controls... But the checklist was interrupted because another fellow had a motor break down in flight, and had to auto down. We spent some time looking it over, and I went back to my Bergen.
After starting the engine, I admit to NOT having followed the checklist. I do not know why. Was it because I assumed it was done? Was it because I felt time pressure to get moving, because the sun would set in only a couple of hours?
As I spooled up, I realized the tail was not behaving correctly. I spooled down, and my buddy saw it before me! Reversed tail feathers!! I could not understand at first, as I had never removed the blades. Then, I understood, and set about flipping the blade grips 180 degrees around. We shut the motor down. I got the ball link pliers, and undid the links, and set them back.
Believe it or not, I had managed to again reassemble the tail incorrectly! And again, I thought to myself, "Jesus! I don't know what's up, but evidently, I'm in too much of a hurry. I better not fly this machine today." And again, I went against my better judgement, telling myself all I had to do was to reverse the blade grips. What could be simpler? So I went ahead, and this time took a couple of minutes to spin the main gear, and check the tail blade rotation, and decided the system was finally assembled correctly.
Engine started again, blades spooled up, I was 100% focused on the tail of the helicopter, which was finally behaving correctly. Except it looked on the ground like the gain was too high. I figured maybe it was due to the slop having been removed. I decided to try it in the air, knowing to be careful. Of course, it would have been even better to lower the gain a tad, before having ever taken off.
At this point, due to the strong winds, I gave some right cyclic, and it looked to me like the wind was gusting stronger, and that the machine needed a tad more right cyclic. I fed in some collective, and the rest of the story took less than a second. I did a 1-inch high side flip, but that's not quite enough height to clear those 710 mm blades. It's only after analysing the remains of the machine that it occured to me that I had already known (but didn't think about!) the fact that when swapping JR servos for Futaba servos, that it is necessary to reverse the travel at the transmitter...
Shame, shame, shame! Of course, I should've done that on the bench. Except I never saw it. I should have caught the reversed control during the pre-flight. Except I never did it. A sad combination of rushing, over-confidence, invulnerability, and self-imposed pressure to get that machine airborne on that particular day resulted in a completely unnecessary and ridiculous crash, from which the only good thing that can come is hopefully avoiding such a blunder again in the future. Returning a machine to service after it has been worked on will not be done again by me without a proper, thorough inspection at home, and without some kind of an "Airworthy!" stamp. There will be no more repairs on the day the machine is to fly either.
I'm glad to say that the machine fared quite well for such a crash. I was quick on the throttle-hold, just about the only positive thing I can say about myself in this whole story. It's still a big crash, but there could've been more damage. It's the first time since I've owned this machine that it is not going home in one piece. I am planning on fixing it to like-new status, and hope this experience will remain with me, and may save other models, and who knows, even some full-size planes, as I am taking lessons towards my Private Pilot's License. It's amazing to think that had I simply done a proper pre-flight, PER MY CHECKLIST, it would have been a "soft" lesson, meaning without the need to actually repair the machine...
Food for thought!
Incidentally, MIF stands for Maintenance-Induced Failure, and it's a technical term which includes everything from improperly closing a radiator cap after checking the coolant level to having a mechanic leaving a wrench in a turbine engine. I believe it may also apply to a doctor leaving scissors inside a patient's stomach
Happy Holidays to all, and take good care with your helis.
My heli spending has gone way down since I got a Honda 919 :-)