A Forced Landing

17 Feb 2005 A Forced Landing

I found this on a great website:
http://www.sdsefi.com/rv12.htm
02/07/05 A Forced Landing

On January 22/05 we were conducting leaning experiments with the WMS wideband AFR monitor and turbocharger compressor temperature measurements with the stainless backplate installed, on a flight between Springbank and Vulcan at 9500 feet. As we leveled off, it was noted that the electronic digital altimeter was changing readings 20-40 feet randomly. This was attributed to rising/ descending air initially. Within 2 minutes, the fluctuations were 100-300 feet but the air seemed smooth. About the same time, I noticed that the WMS meter was reading completely wrong yet the engine was running perfectly. A few seconds later, the GPS went offline. It was recycled but died again within 20 seconds so I shut it off. When I scanned the engine instruments, I noted that the tachometer was reading incorrectly and the Navaid gyro was indicating a right turn when we were not turning. I suspected a charging system failure immediately and checked the battery voltage in the SDS monitor. This read 9.5 volts so I knew then that we had a charging system failure. At the time, I was not worried about making it to an airport, assuming that the alternator had failed just in the last few minutes and believing that I had 20-25 minutes of battery power remaining. In fact, it is likely that the alternator failed soon after takeoff from Springbank but I did not notice signs of the failure until the battery was well over half dead.

Calgary Terminal called to clear us from his zone but his transmission broke up. We could not respond and shut off both comms and squawked 7600 for about 30 seconds before the transponder went down. I shut off all other non-essential electrical loads at this time. I estimated Vulcan airport at 12-15 miles away which we were heading straight for. About 4-5 minutes later, the engine started to run rough as battery voltage was down to 6.5 volts. 2 minutes later, the engine started to cut out intermittently. By turning the low pressure fuel pump off for 15 seconds at a time, partial power was restored for a few seconds. One minute later, the engine essentially ceased running but the prop was still windmilling. I settled on 90 knots as a glide speed with the VSI around 1000 fpm down. About 3 miles out, our altitude looked fine to make the runway, high if anything. 1.5 miles out and it was clear that we would not make the runway. I was worried about 2 ditches, a road and a man made waterfowl dugout off the far end of the runway and did not want to arrive high as we had no flaps. This turned out not to be a problem as we would be well short of the threshold. I made a shallow turn into wind to land in a field parallel to the plowed furrows. Airspeed bled off rapidly in the turn and I had to keep pushing the stick forward to maintain 65 knots. The deck angle was somewhat scary. Don’t stall! don’t stall! was going through my mind vs. the alarming deck angle. At about 20 feet up, I initiated the flare. We touched down level or slightly nose down as there was insufficient stick and energy to complete a proper flare. The nose gear gave way, then the prop and there were some expensive crunching sounds. We slid to a stop on the partially snow covered/ frozen field in about 200 feet.

The G meter read 7Gs from the vertical impact. I used my cell phone to contact Edmonton ATC and report the forced landing. As there were no injuries, we were authorized to move the aircraft by Transport Canada. The local police, EMS and fire services were extremely helpful and efficient. They even arranged for a nearby trucking firm to recover the aircraft for transport back to the airport. Joyline Transport did an excellent job organizing a cherry picker and lowboy at both ends, arranging all permits and getting VZX back to its hangar. Many thanks to all involved from the Vulcan area including manager Wally Walpole, Ken, the talented lowboy driver, the field supervisor and “Woody” from Lethbridge, an interesting personality to be sure. These people made Vulcan the nicest place to have a forced landing and the best of a not so good day.

Preliminary investigation showed that the alternator field fuse was blown for reasons undetermined at this point although some swarf was resting on top of the fuse holder in close proximity. Whether this was the cause or simply disloged from the impact will probably never be known. We’ll be perfoming tests on the charging system when the aircraft is repaired again. The impact sheared the nose leg retaining bolt clean off. The leg punctured the stainless firewall and battery box and came to rest against the battery case. The nose leg was completely “pretzelized” with the tire ending up flat under the cowling. The main gear legs were both bent back an extra 10-15 degrees and the IVO propeller shattered 2 blades on impact. Various wheel pants and fairing were also damaged and both brake rotors were bent. No structural airframe damage was discovered and repair is under way. Thanks to Van’s for designing such a robust airframe and I’m glad I was in a metal aircraft.

Lessons Learned and Applied

Thinking in hindsight on what was not readily apparent at the time of the emergency:

The low voltage warning light was likely ON for 10-15 minutes and remained unnoticed by me because I was busy recording AFR data. The warning light is not a flashing type which is much more likely to attract attention. A 95dB warning buzzer will now be added so that a charging system malfunction will be apparent immediately. I strongly recommend an aural warning vs. a light. The delay in noticing the failure resulted in the forced landing. I believed that I had 20-25 minutes of battery power remaining when the failure was detected but had more like 10 minutes at that point.

Pilots always talk of instructors throwing impossible multiple system failures and emergencies at them in training or in the simulator. Well, this time, we had such multiple, progressive system failures and did not recognize what was happening until the third device started giving odd readings. It is worth thinking about odd readings rather than dismissing them. You might save valuable time.

We rely so much on GPS but the “Nearest Airport” feature does not help much without electrical power and a dark screen. Having a map handy and marking last known position every 10 miles is not a bad idea. Glass cockpit advocates take note on the reliance of these on electrical power. We had no time to Mayday or really squawk a comm failure before power was lost. This could be serious in controlled airspace.

We had no battery backup as this was deemed unnecessary, thinking that the alternator failure would be immediately noticed and that I’d have 20-25 minutes of flight time to find a suitable landing spot or airport. A second 18 amp hour battery will be added with a separate switch, independent of the master solenoid. I was worried that the master solenoid would trip open at the low voltage, effectively signing everything off. Fortunately, the hold current required on these is quite low but this is an extra drain on the battery.

Most of the electrical devices were effectively offline at around 9 volts. Fortunately the SDS ECU and coil pack functioned down to the very last along with the fuel pumps, even at 6.5 volts where the battery is virtually dead. SDS has voltage compensation for the ignition and injector drivers which helped in this situation. Does your ECU have this?

Should I have picked a road or smoother field immediately rather than heading for an airport 20-25 miles away? Well, I would have if I’d known how bad the battery state was.

I should have pushed the throttle up and climbed to get as much altitude as possible to arrive very high OVER the airport but again, I thought I had lots of time.

With total power loss, the aircraft does not glide as well as it does even with idle power. The 3 blade prop has considerable drag due to its flat plate area. This is something you can’t practice, but am aware of now. The deck angle to maintain airspeed is steeper than in training. Maintain speed at all costs and have a margin of extra speed for the flare as the elevators are less effective with no power. Train often for engine failures. It CAN happen to you! I’m glad that I did train fairly often. There was no panic and I did most things instictively.

Wear your shoulder harness! We always do but it is surprising how many pilots are injured or killed with them dangling by their shoulders. Have winter gear with you when you winter fly. We did, even though it was a pretty pleasant, sunny, winter day. Remember, it CAN happen to you!

Use all resources possible. If you have another pilot with you, hand some responsibility over to them for map reading, calling out airspeeds, altitude, reading emergency checklists, giving you flaps etc.

Damage will be repaired. Systems will be changed. Checklists will be altered and training will be intensified. I pledge not to forget the lessons learned here and am very happy to still be here to write this.