A propeller breaking in flight could result in your engine ripping itself off its mounting within seconds.
As with most things that continually perform their duties without any hassles, we generally take the propeller for granted. Yes, we check it for chips and cracks during our pre-flight, but we don’t give much thought to the forces and stresses it endures on a regular flight.
So, what happens when a propeller breaks in flight? A likely scenario is massive vibration, followed by the engine tearing itself off the airframe and the aircraft tumbling out of the sky with fatal results for the hapless passengers.
AN ACTUAL EVENT
In May 2015, a pilot and his wife nearly became one of the latest statistics. This is his story:
‘We live in Upington in the Northern Cape, where I am an attorney. Some clients in Cape Town requested my services, so we decided to make a weekend of it to catch up with family and friends.
Upington International Airport is a dry and dusty place with an obscenely long 4,900 m runway. The runway was built to accommodate a Boeing 747-200 with full fuel, passengers and cargo during the days of SAA having to fly around the bulge of Africa to Europe. Some say it was also one of the alternate airports for the Space Shuttle. Our air force also loves the place, as so do many overseas car manufacturers who race along those long open Northern Karoo roads. It is also now a graveyard for old airliners.
On that Friday morning, I filed a flight plan for a direct VFR flight to Cape Town International Airport. It was a fine early autumn afternoon when I started the pre-flight of my lovely blue and white Cessna C177B Cardinal. While I walked around and tapped this and that and took fuel samples and so on, my wife made herself at home on the right front seat. I finished the pre-flight by pinging the two blades of the variable pitch propeller by flicking it with my nail, as I had done countless times before. It sounded fine, or so I thought.
The takeoff was a non-event, and in case of engine failure after take-off (EFATO), I still had sufficient runaway stretching out below us as we climbed through 5,000 ft – weird. The flight went as planned, except for it being so cold that my wife removed her sandals so as to sit on her feet to warm them.
As we approached Cape Town, ATC cleared me below the TMA to below 1,500 ft, from approximately Fisantekraal Airfield, and from there into their CTA.
I expected to join on a left-hand downwind for Runway 19, but was requested to proceed along to Bottelarey Hills and to keep a look out for a Cessna C150 which was passing below us. I soon had the Cessna visual and was standing by for further instructions.
Bottelary Hills is used for filming and a strange landmark is the replica of a pirate sailing ship, which looks much like the vessel of Captain Jack Sparrow fame. Suddenly there was a ‘pop’ and all hell broke loose. The whole aircraft started shaking. The instrument panel shook so violently that I could hardly see the instruments. Without thinking too long about it, I immediately reduced the power, which probably saved us from losing the engine entirely, thus sparing our lives.
“The engine wasn’t shaken violently, but thankfully stayed attached to the airframe.”
I called the ATC and informed them that we had a suspected bird strike, that the aircraft was shaking violently, and declared an emergency. We were instructed to proceed for immediate joining on the left downwind for Runway 19. ATC then offered the use of Runway 34, which was a much closer option. Below us was a built-up area, with highways and a school rugby field dotted about, but nothing which offered space for a precautionary landing, so I kept on flying with the engine spluttering and shaking.
I didn’t know that the exhaust was starting to break off and the crankshaft was taking a beating.
To maintain altitude, I nursed the throttle as you would a lawn mower to prevent it from stopping. When I applied power, the shaking became so violent that all I could visually identify was Table Mountain, Tygerberg Hills and a runway which was somewhere to my left.
When I reduced power, the shaking lessened but was accompanied by an immediate loss of altitude and the risk of the engine cutting out. I was caught in the classic ‘Catch 22’ – lose altitude, or lose the whole engine.
The shaking was so bad I couldn’t clearly see the runway in the distance. I considered using the GPS to locate runway 34 but I couldn’t use my fingers on the GPS. And in retrospect I probably couldn’t have read the shaking GPS anyway. Sitting inside a washing machine would be better than this, I thought.
As we neared the airport, I still couldn’t identify any runway with certainty, so I requested ATC to give me headings which were promptly given. I couldn’t read the DI and the compass was of no-use with the shaking, but I managed to get us lined up on final approach.
On short final to Runway 19 I noticed two fire trucks, two ambulances and a rescue vehicle all lined up close to the threshold.
I instructed my wife to open her door, and did the same. I didn’t want us to be trapped in the aircraft with jammed doors in case something went horribly wrong.
As I crossed the threshold, I pulled the throttle right back and focused all my attention to the task at hand. The shaking subsided appreciably and I could now clearly see the runway.
It was one of the best landings I had ever done – smooth and on the numbers.
After coming to a standstill, I immediately shutdown the engine. One of the emergency officers pulled open my wife’s door and complimented me on ordering my wife to remove her shoes during the emergency. Walking around the aircraft, I noticed that about 150 mm of one of the propeller blades was gone.
An emergency vehicle towed us safely to the hangar parking. We got a lot of embarrassing attention, but were happy to be safe and sound in one piece.
Later examination showed the damage to the blade was due to a foreign object striking the leading edge, which resulted in cracking and subsequent partial blade separation.
Factors that probably helped me to make the successful emergency landing were the close proximity to Cape Town International Airport, immediate reduction of power, declaring an emergency and the immediate assistance of the ATC.
The aircraft engine had to be overhauled completely and a new prop was fitted. Fortunately, the insurance company contributed to a large extent for the repair cost.’
WHAT WAS LEARNT
- Always expect the unexpected. Complacency could leave you totally unprepared for such events happening to you.
- When doing cross country trips always be on the Iookout for forced landing areas within gliding distance.
- Keep a handy list of alternative airports and charts along of the route with you.
- Check the propeller along the leading edge, and if not happy, always consult your AMO for advice.
- Pre-flights save lives.
- Check your insurance company covers items such as this.