Thread Rating:
  • 0 Vote(s) - 0 Average
  • 1
  • 2
  • 3
  • 4
  • 5
Mosquito accident in Odessa Florida
Quick question to the guys who have broken a fan, is there evidence of the fan rubbing fan shroud prior to fan blade breaking?

Dave Storey
Not in my case. The shroud was unmarked.
No, i had no indication of rubbing before it broke.
Me neither
XE285 #1329 N869DJ
Start: June 2018
Done:  Sep 12, 2018  Sleepy 
AWC Issued: Sep 26, 2018  Big Grin  
Post #26 is not accurate at all. I was the pilot of that mosquito and let me tell you, pre flight and lack of maintenance was not the problem. As a license helicopter pilot, I know how to do a pre flight as I did in this case. I used the best and recommended oil for the 285 and lack of maintenance is far from the truth. Yes, the high temp indicators went off and I started my decent immediately. Unfortunately the engine seized up very soon afterwards. So to clear the air.....This was not pilot error. The pilot training is what saved my life.
Listen, Im a huge fan of the mosquito. And the factory and gentlemen that work there that so very much helped me with my build are TOP notch. Im actually considering building another, but it will be the XET.
Thank you very much for posting.

I told a friend that also owned a Mosquito that I doubt the crash had anything to do with pre flight inspection. And as far as the warning buzzer or light on the dash I would consider it to be useless. Good luck hearing it with a helmet on and seeing the red light with the sun on it. The same thing happened to me, after flying for 30 minutes the engine ( MZ202 ) locked up while hovering about 15 feet up. I did not hear the buzzer nor did I see the light. And it happened so fast after seeing the gauge it was to late. I also told my friend the XET is the only one I would feel comfortable flying in. While I understand the Mosquito is experimental I also feel the factory should inform every owner by e mail or phone when a issue such as overheating happens and the cause. At the very least they should inform other owners. 
I also think the cooling fan should not be mechanical. The belt, pulley or fan blade can fail. If the radiator was redesigned to be mounted under the cab with a scoop design it would cool the coolant without needing the fan while flying and an electric fan could be used with a temp sensor to operate it only when needed.
Thanks for responding to this thread.  It is always so important to get any first hand knowledge of any accident.  Glad you were able to get it down and walk away.  I really enjoyed your videos on youtube.
I have always been leery of 2 strokes but the 285 intrigued me.  It seems like a pretty good 2 stroke but there are always problems when you start converting other engines for aviation use.  I am surprised the Europeans are the only ones to use the Rotax 912.  It is a shame there is no middle ground helicopter, you get either a 2 stroke or turbine.

Do you know the cause of the failure?  Was it oil? or the fan?

Odessa Event response 1-27-2020

        As all of you may know I do not spend a lot of time on this forum, but sometimes I feel the need to respond. One reason is I am not an English major, so if spelling and grammar are your most important assets - this is not for you. I only hope what I write will help you understand the point being made and if not let me know and I will try to clarify it.
      Upon choosing a fan for the 285 in the beginning many considerations had to be taken into account. Safety point of preventing a failure and if there was a failure not to make things worse if it happened in flight. The fan we use on the 285 is rated for 8,000 rpm, and before using this fan I made a fixture to install it in our Haas CNC vertical mill. This blade was tested at 10,000 rpm’s for an extended amount of time to verify its structural integrity. This blade starts life out as a 17 inch fan that is cut to 10.5 inches which makes the hub over constructed for the smaller diameter. Finding the reason for fan failure began with the question of how can some machines run hundreds of hour with no failure and others no more than ten? After much consideration and looking at failures and testing, it is our determination it is caused from incorrect fuel mapping at a particular rpm causing the engine to go into a fuel induced oscillation. As kids we all remember spinning a bicycle wheel while holding it by its axle. At the same time not being able to move the axle off its axis as the wheel spins. With the 285 the crank shaft is spinning up to 6000 rpm along with the fan then the crank goes into an isolation putting forces into the fan trying to move it out of its plane that it does not want to go into causing fatigue on the fan blade until it fails. So the issue is not the structure of the fan - a stronger steel fan will also fatigue. Now you have a 6000 rpm steel ring destroying everything in its path until it stops which is not the answer. Electric fans where looked at and tested extensively they simply will not work as they cannot move enough air at hover to cool the engine. Air scoops will also not work because of the power demands on an engine installed in a helicopter. Unlike fix wing, cars, trucks etc. Helicopters use the most amount of power  hovering (vectored thrust), producing the most amounts of heat or BTU’s at zero mph. After going through ETL into cruise the power demand decreases making the least amount of heat or BTU’s in the flight envelope.
            There are two cures: one is to correct and fine tune your fuel mapping to avoid the engine oscillation. Even though we have had success here at the factory at the mapping it has become clear some customers lack the proper skill set, patience and understanding on how to accomplish this at their location. This can be a frustrating task to the new guy.  As flying conditions change the fuel mapping also has to be adjusted for those conditions. So cure #2 in our opinion the final cure is to make available a fully programmable and automated ECU for the engine. This ECU will operate vary similar to the one that is in all modern day vehicles. Once the base program is uploaded the ECU will do all the tuning in real time even in flight. We are in the middle of developing this system and hope to show it at our annual fly-in this year. 
            As far as warning lights and or buzzers in the dash being useless to the pilot seems to be a ridiculous statement on its face value. No matter what aircraft you fly from a Jet Ranger to a Boing 747 or an Airbus 380, industry wide warning buzzers and lights are used. As a pilot you are trained to scan your instruments every few seconds. If you do this, missing a warning light or buzzer should be very unlikely. If you are having this problem not monitoring your gauges properly I would encourage you to get the proper training or consider this hobby may not be for you. Flying any aircraft should not and cannot be taken lightly and having the proper skills is a must including knowing how to perform a proper autorotation and practicing it.
        Knowing your aircraft and noting performance changes is also key to many safe hours of flying. Since Mr. Witkowski brought his story up I think it is a good one for educational purpose. Please keep in mind the purpose of this forum is for educational purposes not to embarrass or belittle anyone in any way. From my recollection Jim bought his machine used and spent a lot of time on it making it a beautiful XEL. Before my involvement he had an overheating problem which he and another XEL owner in his area worked on. This problem persisted causing a piston to seize. After purchasing new parts from the engine manufacturer and reassembling the engine the problem persisted. Jim ultimately sold his machine and the new owner had the same issue - frustrated he brought the helicopter to the factory to get looked at. After going through the engine we found a small piece of plastic lodged in the inlet barb to the carburetor on the cylinder that was overheating. After removing the fuel restriction I hovered the machine for an hour before returning it to the owner. As a diagnostic exercise, once the base engine was repaired the first time and the issue persisted, a deeper dive into the fuel delivery system should have been warranted. This story is to only demonstrate on how important it is to know the systems on your machine and make no assumptions on pre-flight, post flight and repairs.
        In regards to the accident, the FAA and the NTSB are not required to come to a conclusion in any accident. I was not in the aircraft or even in the area at the time of the accident. If there is not clear evidence that shows a clear cause then it is only speculation and as any good agency should do is not conclude anything on speculation. The owner and operator of this aircraft was the only one there and I would consider him a friend. I received a call from the NTSB to help in the post-accident investigation, which as always I accepted. In a briefing from the FAA investigators they provided pictures and notes from the on sight investigation. They noted the pilot had said the engine stopped in flight with no indication of trouble. They also noted that upon impact the tail rotor and main rotor were not turning (zero rpm). Adam and I met up with the investigators at an FAA hanger on the east coast of Florida where the wreckage had been taken. Based on the information with which we started, was there a mechanical reason a proper autorotation had not been accomplished. All bearings and flight controls where inspected for function and or mechanical failure. It was determined no mechanical failures where found in this area previous to impact. We then turned to instrumentation - the electrical system was still intact and it powered up. Then all data from the data logs was down loaded and retrieved, turning our attention to the engine - we removed the spark plugs first to look for a lean or rich condition. We verified that the fuel system was intact and that fuel and oil was onboard in tanks prior to impact. Inspect all components to the engines cooling system. We disassembled the engine to inspect the damage on internal components caused by the engine stoppage.
      Conclusions are based on facts collected over the years in some cases, but most were based on the facts collected in the investigation. It is not unusual for post-accident data to not match up with witnesses or onboard survivor accounts. Call it the fog of war or being overwhelmed at the time, it happens to all of us including myself. After a mechanical failure in flight - with flight controls intact - a proper autorotation would result with main rotor rpm still turning between 80 to 110 percent upon contact with LZ . In this case it did not happen and the reason is unknown but it did not appear to be mechanical. The inspection of the spark plugs indicated a slightly rich condition but not excessive and no indication it would cause an engine shut down. Color indications inside of the exhaust tubes were the same as the plugs. The fuel cell still had fuel in it as did the fuel lines and injectors indicating fuel was available to the engine components. Internally on the engine one quarter of one piston had melted and broke off the piston head. The tops of both pistons had heat detonation marks on them. The engine showed no signs of seizing but exhibited scoring on the cylinder that the piston was damaged. All cooling hoses where melted off the engine leaving some melted residue at the hose clamps. The hoses are rated up to 275 degrees with operating range between 195 to 200 degrees. The data retrieved from the electronic flight logs indicated coolant (engine) temperatures reached as high as 600 degrees before data logging was terminated. Why the engine quit can be a couple reasons: the current ECU is equipped with three limp modes or self-preservation modes. The first is tripped at just under 190 degrees which the ECU will over fuel by 10 percent and retard the timing by ten percent. In this first limp mode the helicopter is still flyable which I have done several times but the engine will run quite rough. If the conditions persist the second limp mode will continue to add fuel and retard timing even more. If it is left unchecked the third mode will force the engine to an idle and the operator can do nothing to change this condition. We can only speculate at this point why the engine quit. It could have gone into this final limp mode or the piece that came off the piston could have lodged in the rotating assembly stalling the engine. The final answer we may never know as well as what caused the engine to overheat in the first place. But, as the data showed from the time the engine overheated, tripping the warning at 185 degrees, to the point that all hoses melted off and the indicator reached 600 degrees, should have been ample time to react. The main reason we volunteer to help in these investigations, at our own expense, is to see or find failures that can be improved upon. If we were trying to hide something as indicated by some, the FAA is there for the inspection and to keep that from happening, (as they should). In the end, no aircraft can guarantee not fail at some point - nor the pilot, as in the news today where a very tragic S-71B helicopter accident in California took all souls onboard. This is one of the most sophisticated helicopters and has been in production for many years. Whether this accident was caused by mechanical failure or pilot error - it only reminds us of the risk all of us take each day including driving down the highway.
        In regards to the 285 engines and seizing we have repeatedly leaned this engine out to the point they quit running and have never had one seized up. There are two reasons for this: one being liquid cooled keeps the thermal dynamics more even throughout the engine in its operation (no hot spots). The second is the oil injection continually injects oil into the engine regardless of a lean condition making seizing much less likely. To say you cannot seize this engine would be an over statement but we have not to date seen it happen. For these reasons liquid cooled fuel oil injected two strokes have proven to be as reliable as there four stroke counter parts.
[attachment=2729]         After reading Dwight's post I decided to explain the circumstances behind my incident.  I purchased the XEL from an ad on Barnstormers. There was a picture of it and the ad stated it was a factory built machine built for Lynn Watkins which was a factory dealer. The ad also stated it was "the best running machine out there". Because it had been factory built for a dealer I purchased it site unseen and had it shipped to me. The helicopter had 11 hours on it when I received it. Upon delivery I noticed the tail was painted all white and in the picture in the ad it was two tone, white and green. When I questioned Watkins he said it had been replaced due to an incident. His explanation was very vague. I decided to have it repainted the way it left the factory. After it was redone I also discovered it didn't seem to run very well either. When I questioned Watkins about it he claimed it ran perfect when he had it. The only thing I did was started it up after the paint work. I discovered the case was leaking. I resealed the case and upon running it again it seemed to run better but still not perfect. So after removing the heads I discovered a piston was damaged and replaced both with new ones. It seemed to run better after that. At 13.1 hours the engine froze up. Upon disassembly I discovered a hole in a piston. I called John Uptigrove and discussed the issues with him and also suggested he revoke Watkins dealer contract. John was very helpful and apologetic for what seemed like a misrepresentation of this machine by Watkins. John suggested replacing the short block with a new one which I also did. After spending $4000.00 on mechanical repairs and another $1000.00 on interior and paint improvements I decided to sell it. It ran fine when I sold it to the new owner. We went to an airport near me so he could see it run and fly. If John was still with us he could speak to what happened as I was in contact with him through out the repairs.

Forum Jump:

Users browsing this thread: 1 Guest(s)