It is reputed that the Pilatus PC-6 Turbo Porter was designed by a committee of six Swiss farmers to carry hay into the high Alps, so that they could keep their cattle up there for longer. They knew pretty well what a hay cart looked like but didn’t know much about aeroplanes.
The whole point of the Porter was to carry a ton of hay up as quickly as possible, land almost anywhere and get back down for the next load. Speed was not a requirement, which may account for the Porter’s nickname, ‘The SOS’, or Stationary Object in the Sky.
Quite apart from being a box with wings, the Turbo Porter has an extremely long nose, as though the designers wanted to get the noisy bit as far away from the pilot as possible. The wings don’t actually fit onto the box very well, so they have to stick a bit of pinked tape over the gap.
So that is the first impression, but on closer inspection this ugly duckling hides some remarkable secrets…you can take the passengers’ seats out of the ‘Box’ and stack them on seat rails hidden down the back, in the tail.
There is even a bomb bay with doors which can be opened and closed by the pilot, in flight. On the current model the passenger cabin has enormous sliding doors on each side which can open the full length of the cabin to the wind, during flight, which makes it very convenient for ejecting parachutists, unruly passengers and out-sized loads. The cockpit doors are designed to be released during flight, if the pilot decides to go parachuting too.
Then there are some interesting little details:
For example, the ailerons, flaps, elevators and rudder can all be built on the same jigs. The massive main undercarriage has almost a foot of travel on its oleos, allowing operations out of places which would destroy most aircraft and if the landing ground is too rough even for them, they are designed to break away without taking any of the other important bits with them…and Yes…I have actually seen that happen!
And then there is the best kept secret of the lot, the engine. The originals had a great big geared, 6 cylinder, 345 hp Lycoming stuck to the fire wall, but the Porter was so slow that the engine would overheat, particularly in the tropics, so, after playing around with the Astazou and Garrett turboprops, Pilatus discovered the legendary Pratt & Whitney PT-6 (‘Pump Turbine No 6’) which had been pumping oil on a pipeline in Canada non-stop for many years and seemed like an ideal candidate for conversion into an aero engine. It churned out 720 shp and weighed less than half the old piston engine, which is why they had to stick it so far out in front – to balance everything up.
I have spent more than 6 000 hours of my life sitting in the front end of the old girl and I have never ever had my faith in the engine tested. As WW2 American pilots used to say…”Put your trust in God and Pratt & Whitney.”
The old Porter has saved my life on so many occasions that it is difficult to pick out a single example, but just to give you a flavour, I was flying for the Canadian Occidental Oil Company in South Yemen in 1994. They had a production site up in the wild, barren mountains in the Hadramaut Governorate.
The pipeline to bring the oil from the site down to the coast started at 3600 feet above sea level and climbed to 5800 feet before plunging down a 2000 foot escarpment.
The pipeline followed a fault line which formed a kind of ramp down the escarpment at an angle of about thirty degrees down the face of the cliff. The pipeline was accompanied by a dirt track known as the ‘Right-of-Way’, which was approximately twenty feet wide and made the total width of the ramp, with the pipeline, about thirty feet between the face and the drop-off. This provided enough room for a Land Rover, as long as the driver had had a quiet night the night before.
Ken was driving on the day of the incident I describe. There was a loss of pressure on the pipeline. This would involve a pipeline inspection and so he took Ibrahim, a Libyan pipeline engineer (whose father had been ‘disappeared’ under the Ghadaffi regime) and a couple of workers in case it was simply a matter of lifting something.
They drove all the way down to Station 88, which was about halfway to the coast. It was on the way back up the escarpment that the incident took place.
Ibrahim was standing on the tail-gate footrest, so that he could jump off and back on again at each joint. It was as Ken pulled away from one of these joints that Ibrahim’s feet slipped off the footrest and hit the ground, driving his face down onto the step.
Nobody noticed Ibrahim’s absence until they reached the next joint.
Ken initially thought that Ibrahim had just gone to excuse himself, but after ten minutes, he became concerned and started walking back down the right-of-way. He found Ibrahim, unconscious, lying face down in the middle of the track. There was blood on the ground around his head. Ken suddenly realised that he was facing a career-changing emergency, possibly a fatality.
He ran down the hill, hollow fear punching at his diaphragm. His first worry was whether Ibrahim’s neck was broken. If it was it was, it would be extremely dangerous to move him. Ken knelt down beside Ibrahim’s head and leaned forward to listen for signs of life. To his enormous relief he detected faint and stertorous breathing. There were teeth mixed in with the blood.
“Can you hear me, Ibrahim?” He said but there was no reaction. “If you can hear me, stay still. We are going to get you back to the clinic.”
Then Ken raced back up the hill to the Land Rover and called Base Camp.
“Hello Base, this is Mobile One.”
“Hello mobile one, this is Base. Go ahead.”
“Roger Base, can you call the medic to the radio…urgent.”
“Copied. Stand by.”
Seconds later Jim, the Medic was on the line. “Mobile One, Medic, go ahead.”
Ken explained the situation, including the possibility of a broken neck. “Mobile One, that’s all copied. Keep the patient immobile and we’ll be with you as soon as possible.” He then pressed a series of short blasts on the camp siren, which was where I came into the story.
I raced to the Radio Room and Jim filled me in on the details. “I have the vacuum stretcher and the emergency bag ready. What we need to do is to find somewhere to land as close as possible to the patient,”
I nodded, and we were airborne in minutes.
I had often wondered if it would be possible to land on the ‘Right-of-way’ on the escarpment and today we would see.
I had made several approaches on previous occasions and it looked do-able if the wind was quiet. Today there was no wind and I gave Jim an enquiring look. He nodded as he tightened his harness. “Let’s give it a go,” he said.
We lined up just off the lip of the ramp, about three hundred metres below where Ibrahim was lying. I selected ‘Take-off’ flaps and started to climb up, with the ramp just outside my window.
When we appeared to be climbing at the same speed as the ramp, I slid across until we were over the track and kept pulling back on the stick until the Old Girl eventually just gave up flying and sank onto the ramp. The left wing tip was a fairly comfortable two metres away from the cliff face and the right main wheel was locked in the right hand rut of the track, a good couple of metres from the edge of the ramp.
By the time the wheels brushed onto the ground we were almost stationary and I had to add a lot of power to get up to Ibrahim. I closed the engine and electrics and pulled the hand brake cable to lock the brakes, before I jumped out and chocked the wheels. Then I opened up the back and Jim jumped out, grabbed his First Aid bag and went to have a look at our patient.
“Could you bring us the stretcher, Hugh.” Jim shouted.
I lifted it out of the cabin and took it over to where Ibrahim was lying. The ‘Vacuum’ stretcher is like a great big bean bag which assumes the form of the patient. Then it has a little air pump which extracts all the air and the bag grips the patient firmly enough for him to be manoeuvred without risk of further damage. It took the six of us to lift Ibrahim extremely carefully into the stretcher, pump the air out, strap him in and jump aboard, after quickly checking to make sure that all the important bits were in place.
There was no space to turn the aircraft around without falling off the ramp or banging a wing on the rocks, so it looked like we would have to taxi up to the pumping station, halfway up the escarpment. There was parking for a truck up there and that should give us room to get the old girl facing down the hill again. I started the engine, completed the pre-flight checks and set off up the hill using almost 30 psi of torque just to keep her moving. Eventually we reached the pumping station platform and I swung the Porter round until it was pointing in the other direction. I lined up carefully on the twin ruts of the Right of Way and allowed it to freewheel down the hill. Immediately the Airspeed Indicator needle began to flicker, I raised the tail, increased the engine torque to 35 psi, selected Take-off Flap and it just floated into the air.
It really was that simple.
We got Ibrahim back to base and discovered that his jaw was broken in three places, five teeth were snapped, although none actually came out, his nose was broken and both his cheek bones were driven into his face…but, by some miracle, his neck was not broken and I still get a birthday card from him every year…
Al Hamdu L’lllah, as they would say in Bradford.