I’ve never hand propped an airplane, so I don’t know that thrill. I used to jump-start my manual transmission cars by popping the clutch. It’s not quite the same, but from that I think I can approximate the rush that comes from spinning life into a dead airplane.
In this day and age, should you hand prop an airplane if other conventional methods don’t work in getting the motor running? That’s a solid maybe in my book. The question isn’t can you. It’s should you?
It’s kind of like determining the difference between “legal to fly” and “safe to fly.”
There are airplanes that are specifically designed to be hand propped. Those that are have the procedure outlined in their Pilot Operating Handbooks (POH).
Almost any reciprocating-engine airplane can be hand propped, theoretically. That goes for singles and twins. I write “reciprocating-engine airplanes” to differentiate from turboprops.
The key piece of gear behind hand propping capability is not having a propeller, but having magnetos. Magnetos are small electric generators containing a permanent magnet and are used to provide current for the ignition system of spark-ignition engines. Magnetos produce a high-voltage pulse used by the spark plugs.
Clutches on cars and magnetos both date back to the Wright brothers’ era. Clutches and stick shifts are all but obsolete in passenger cars now, thanks to the technological evolution of starter motors and transmissions. We’re well past magnetos in engines, too, so why do airplane engine makers still manufacture them?
Three reasons: They’re cheap to make; they last a long time; and — most of all — because magnetos work even when the ship’s battery and alternator are dead. If you can get the engine started, the magnetos will keep it operating until you decide to make it quit.
More importantly, if all of your electrical systems fail in flight, your magnetos will keep the spark in your ignition system going, allowing you the opportunity to land safely.
Just one more thing: To properly start an engine using the hand propping method, the correct magneto switch must be in the “on” or “hot” position. It’s the one that has an impulse coupling attached to it.
How do you know which magnetos are correct? Generally speaking, the standard configuration for aircraft engines is the left magneto set.
Let’s go back to the “if you can get the engine started” part and “should you” hand prop question. The three rules of thumb for hand propping are:
- Don’t get hit by the propeller.
- Don’t let the airplane get away.
- Don’t be stupid.
A Cessna 172 pilot decided to include a flight to North Carolina’s Outer Banks as part of a family vacation. He flew the group to First Flight Airport (KFFA) to visit the Wright Brothers National Memorial. He parked and chocked the plane, but forgot to turn off the master switch, so by the time the family returned from their tour, the aircraft battery was dead.
The pilot went into the local FBO and asked for some assistance. No battery was available for sale, so the hand prop alternative was raised. The FBO manager — an A&P — declined the request to hand prop, but another pilot “eagerly stepped forward and said he would be happy to hand prop the plane.”
The Cessna pilot got in the cockpit while the volunteer positioned himself by the propeller. He then instructed the pilot to turn on the master switch, which the pilot did. The volunteer pilot pulled the propeller through several times unsuccessfully.
The volunteer pilot stopped and returned to the cockpit door to inspect the position of the master switch.
“I was thinking that we should be positioning the magneto switch and not the master switch,” wrote the Cessna pilot in a report to NASA’s Aviation Safety Reporting System.
The volunteer pilot instructed him to put the key in “start” when he pulled the prop through. The Cessna pilot complied and the motor started.
“I do not remember if he was pulling the prop through or positioning it,” the pilot continued in his report. “As he jumped back from the prop, he shook his hand as if he had hit it on something. Only when he came around to the side of the plane did I see blood and realize he was injured.”
It turns out the volunteer pilot broke a bone in his hand that required surgery to fix it. He was lucky. He could have lost his hand or arm — or worse.
The pilot wrote in his conclusion, “It is now obvious that he did not really understand what he was doing. If this ever happens again, I will wait for a new battery.”
Another pilot categorized his hand prop misadventure as “another stupid, it-won’t-happen-to-me scenario.”
He planned to join friends at a fly-in breakfast. He pushed his plane from its hangar onto the grass airfield’s wet, green ramp area. A weak battery prevented the plane from starting normally, so he decided to hand prop it.
“I’ve hand propped it a few times, but only once before by myself,” he wrote in his NASA report.
Still, with nobody around and a desire to share breakfast with friends strongly motivating him, he made the attempt. He was unsuccessful several times before the motor caught and started. The prop blast slammed the cockpit door shut before the pilot could climb in. When he did get the door open, it separated from the plane, and he slipped and fell on the dew-soaked grass while the airplane accelerated away.
It eventually hit his hangar, the prop striking the hangar’s wood frame and metal covering. The aircraft’s left wingtip was crushed and the right wing fabric damaged. The prop striking the hangar also caused sudden engine stoppage, which necessitated a teardown.
The pilot cited as contributing factors failure to chock the wheels, failure to tie down the tail, and failure to wait until later for another person to assist.
“The cause of this is easily the poor judgment I had shown by trying to attempt this whole flight,” he concluded.
Some Aeronca Champ airplanes don’t have an electrical starter system. A normal way to start those Aeroncas is the hand prop method.
An Aeronca Champ pilot claimed in his report that he had hand propped his aircraft hundreds of times in the past. This time he asked a lineman to help hold the Champ’s tail while he conducted the hand prop procedure.
After an unsuccessful series of propeller pulls, the pilot determined he’d flooded the carburetor. He shut off the ignition and pulled 16 blades, per his training. He then turned the ignition switch back on.
“It started on the first pull and went to full power,” he wrote in his NASA report.
The lineman couldn’t hold the plane as it was moving, so the pilot ran back toward the cockpit to retard the throttle. He did, but not before the plane turned and plowed into a Beechcraft Sierra. Both airplanes were damaged.
Each of these NASA reports violated at least one of the three rules of thumb for hand propping an airplane. But these are not isolated incidents. I read through scores of similar tales of woe.
One pilot wrote in his NASA report: “I feel that more emphasis should be given to this procedure in primary training and that it should be discouraged.”
I can think of precious few reasons why a pilot would absolutely have to hand prop an airplane. Those reasons include fleeing from war or a natural disaster.
The pilot of a Commander 100 decided to hand prop his airplane after briefing his non-pilot passenger on how to retard the throttle, close the mixture, and turn off the ignition switch. However, when the pilot pulled the propeller through and the engine started, the throttle was open enough to allow the airplane to jump the tire chocks.
The pilot was unable to get back into the plane. He held onto a wing strut as the plane accelerated, eventually taking flight.
The pilot wrote that he “let go of the strut and abandoned all hope of entry into the airplane.” He fell to the ground. The plane settled back onto the ground, struck a berm, and flipped onto its back. The passenger suffered multiple facial fractures.
A resilient soul, this pilot concluded, “I will certainly never hand prop another plane without taking more precautions (tying the tail) and giving consideration to worst case scenarios, such as passenger panic factor impeding their actions.”
But did he miss the point?
In the 1950s an FAA cameraman happened to be filming at an airfield when a pilot decided to hand prop his plane while a non-pilot remained on board. The video is now on YouTube. It’s worth a watch, or two:
I understand there may be far more examples of pilots successfully, safely hand propping an aircraft than there are those who had to file NASA reports.
That still begs the question of just because pilots can, should they? After all, hand propping often masks larger issues, like an electrical system failure, get-there-itis, or just poor Aeronautical Decision Making (ADM).