According to the student pilot, he and the flight instructor conducted a preflight inspection, start-up, taxi, and engine run-up of the Piper PA-28-181, which included two checks of the carburetor heat system.
Once they received their takeoff clearance, they began the takeoff roll on Runway 21R at Dekalb-Peachtree Airport (KPDK) in Atlanta and, after rotation while around 200 feet above ground level, the engine started to “sputter.”
The CFI took control of the airplane as the engine lost total power.
The flight instructor told investigators that after the engine lost total power, he initiated a left turn to avoid colliding with structures.
The airplane hit the ground on the right side of Runway 3R, resulting in substantial damage to the fuselage and wings.
The flight instructor sustained serious injuries and the student pilot sustained minor injuries in the crash.
Data downloaded from an Electronics International MVP-50P engine data monitor indicated that carburetor temperature decreased to 40°F and then increased twice before the takeoff. Then, during the takeoff, the RPM increased to 2,600 and the carburetor temperature decreased to 38°F for about a minute.
At the same time, the fuel flow increased, surged three times, and then decreased to 0. Furthermore, the engine RPM remained around or below 1,500 rpm for the majority of the flight except two times, when the RPM increased to 2,000 and 2,600 rpm.
The weather reported at KPDK at the time of the accident included a temperature of 23°C and a dew point of 14°C. The calculated relative humidity at this temperature and dew point was 57%.
Review of the icing probability chart contained within FAA Special Airworthiness Information Bulletin CE-09-35 revealed the atmospheric conditions at the time of the accident were “conducive to serious icing at glide idle power.”
According to FAA Advisory Circular (AC) 20-113: “To prevent accidents due to induction system icing, the pilot should regularly use carburetor heat under conditions known to be conducive to atmospheric icing and be alert at all times for indications of icing in the fuel system.”
The AC recommended that when operating in conditions where the relative humidity is greater than 50%, “…apply carburetor heat briefly immediately before takeoff, particularly with float type carburetors, to remove any ice which may have been accumulated during taxi and run-up.”
It also stated, “Remain alert for indications of induction system icing during takeoff and climb-out, especially when the relative humidity is above 50%, or when visible moisture is present in the atmosphere.”
Probable Cause: The flight instructor’s failure to effectively utilize carburetor heat, which resulted in a total loss of engine power during initial climb due to carburetor ice that formed during the engine run-up and taxi.
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This February 2023 accident report is provided by the National Transportation Safety Board. Published as an educational tool, it is intended to help pilots learn from the misfortunes of others.
My experience with carb ice:
June flight. Afternoon surface temps upper 80s.
I was bringing my Ercoupe back from annual in Texarkana, headed to base at a grass strip near KTME-Houston Executive.
It was a warm, muggy day. A few cumulus around. I was cruising about 6500 feet. I was cleared into the IAH Bravo at 5500. Shortly after entering the Bravo, I was told to quickly descend to below 2500 feet. I chopped power and the Ercoupe came down very quickly.
When I went through 2500, I added power. Nothing happened. The engine was running but only idle, unresponsive to throttle. I had great forward speed coming off that descent so I was pretty much maintaining altitude. The tollway was in front of me so I had a place to land. I had a brief thought of being “That Guy” who ends up on the Six O’clock News.
Honesty, there was no panic. I had a plan for an emergency landing. I had not yet advised Approach of my situation I kept watching the tach when I tried the throttle. Then… the engine responded! I had full power!
This all took place in less than a minute. (Seemed much longer). I had only lost a couple hundred feet. I flew the remaining 25 minutes home. Put the Coupe away. Grab a beer out of the fridge, and sat down to unpack the event. I just couldn’t figure out what happened. I call my A&P/IA/Ercoupe guru and filled him in. He quickly said “Carb Ice!”
Then it hit me. Of course! The rapid descent, at idle power, of 3000 feet in high humidity conditions. It was the perfect recipe for carb ice.
And, to my shame, it never once crossed my mind. I typically fly in the warm, muggy Southeast Texas environment at relatively low altitudes. 2500 or so. I always use carb heat in the pattern when I reduce power. But this slam-dunk in the Bravo was unexpected.
I think what saved me is that, when I got to 2500 feet, I eased the throttle back in. Had I jammed it in, I might have killed the engine. As it was, I think the heat of the engine and the outside air temp eventually thawed the ice before things got too dicey.
I should have known better. I had over 300 hours at that point. Half of that time in the Ercoupe.
Fortunately, I lived to learn the lesson and tell the tale.
Carbureted engines will experience icing – aircraft, cars, boats.
My VW Beetle would ice up the carb on a cool, humid day. You could watch the ice form on the outside of the carb.
My Cessna has a carb temp gauge and on starts on cold days, the needle is in the icing zone. So, I use carb heat shortly after starting and part way taxiing to the runup area.
What is really disturbing is how ignorant much of the pilot population is about carburetor icing. It’s as if the carb icing probability charts had never been published.
Of course, the Piper POH advice on the use of carb heat is woefully inadequate, too.
Interesting. In 48 years flying Lycomings in Pipers, Cessna, and Mooney I’ve never used carb heat. Even with airframe and prop iced to the point of unable to hold altitude.
When will the dangerous myth that Lycomings never experience carb icing die?
It might be a myth, but I never experienced carb icing in the Cherokees I used to fly while earning my license, nor later in the Yankee I owned. Cessnas, on the other hand…
In my opinion, first aid for any engine stumble is carb heat. Plus the usual other remedies like switching tanks, etc. It’s icing until proven otherwise, but I personally never had any in a Lycoming.
My initial training was in a Cessna 152, with the Lycoming O-235, which would ice up the carb on most flights in SoCal…
My C175 with a Continental GO-300 will ice the carb, on initial taxi to the runup area.
It has a carb temp gauge, and I’ve had it go into the ‘yellow’ icing zone at altitude as well.