According to the pilot, a 100-hour inspection had just been completed on the Piper PA-28-181.
The pilot told investigators that the engine run-up was completed with no anomalies noted.
After liftoff, he remained in the traffic pattern for Runway 31 at Livingston County Spencer J Hardy Airport (KOZW) in Howell, Michigan.
The first traffic pattern and touch-and-go landing was uneventful.
On the second traffic pattern, the pilot extended his downwind leg by five seconds for spacing from another airplane in the traffic pattern. When he pilot reduced power and added 10° of flaps for the descent, he noticed that engine rpms had decreased to 900.
He attempted to restore engine power by turning on carburetor heat and verifying the electric fuel pump was on.
He was unable to restore engine power and transitioned to attempt a forced landing to Runway 31. During the forced landing attempt, he glided underneath powerlines and over the airport perimeter fence.
The airplane touched down in the grass short of Runway 31. It bounced on an embankment, hit the localizer antenna, and came to rest upright 1,000 feet before the arrival end of the runway.
The right wing separated at the wing root. The left wing was damaged and leaked fuel.
The carburetor linkage was connected and moved freely. The carburetor heat valve moved freely from open to closed.
The electric fuel pump was tested and fuel flow was noted from the output line. Fuel was present throughout the fuel system, carburetor, and fuel filters, and no water or debris was detected in the fuel. The engine-driven fuel pump was observed to pump fuel during engine rotation. The carburetor accelerator pump had positive pressure during manual actuation.
The fuel selector moved freely to all positions. The oil filter was new and appeared to be installed properly. An oil sample was obtained and no contaminants or metal were noted. The engine’s crankshaft was rotated by hand and internal and valvetrain continuity was established. The top spark plugs were removed from the cylinders and remained attached to the magneto leads. The spark plugs produced spark when the engine was rotated.
At 10:35 a.m., the weather reported at KOZW included a temperature of 22°C and a dew point of 20°C. The calculated relative humidity at that temperature and dewpoint was 88%.
Review of the icing probability chart contained in FAA Special Airworthiness Information Bulletin CE-09-35 revealed that the weather conditions at the time of the accident were “conducive to serious icing at glide [idle] power.”
According to FAA Advisory Circular 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 circular 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: A loss of engine power due to the formation of carburetor ice that resulted from the pilot’s delayed use of carburetor heat during the landing approach.
To download the final report. Click here. This will trigger a PDF download to your device.
This June 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.
Sorry, but I’m a glider pilot and fly antique SEL aircraft. I always have the runway ‘made’ if I am in the pattern. These half power/half flaps approach to landing are going to end up like this if there’s a loss of power. If you’re flying an instrument approach, you need power to maintain the glide slope in most GA aircraft. But a VFR approach should be made with power at idle and the runway within gliding distance at all times if you have a power failure.
One of the problems is that the airplane flight manual for the PA28-181 says: “Carburetor heat should not be applied unless there is an indication of carburetor icing, since the use of carburetor heat causes a reduction in power which may be critical in case of a go-around. Full throttle operation with carburetor heat on is likely to cause detonation.” This is a common statement in PA28 flight manuals equipped with carburetors. There have been several accidents due to carb icing in the PA28 series. Once carb icing is suspected in the traffic pattern, it is often too late to do anything, hence the accidents. The NTSB and the FAA in the form of AC and SAIB have recommended using carb heat as a preventative. However; many pilots and CFIs are hesitant to do something in contrast with the flight manual. I would say using good ADM and risk management principles would be to use carb heat, but be careful to turn off carb heat during a go around and not use at full throttle.
The club I fly with has both an Archer and a 172. I’ve wondered about the differences between carb heat usage between them, but never seen a good explanation. This answers a lot of questions. Thanks.
The Marvel-Scheber MA4-5 carb has a fitting that is used to attach a carb temp sensor with an analog gauge. It’s worth adding the accessory.!
Here is Northern California, in our colder months [35-40 degF], after a cold start, the temp gauge goes into the ‘Yellow’ zone, so I have to use partial carb heat while taxiing to the run up area.
Once the oil warms up the carb temp rises above the icing zone.
I’ve used partial carb heat at altitudes where the temp is close to freezing.
The Lycoming O-360 180 flat-4 engine is one of the •least susceptible to carburetor ice• so this should stick in flight instructors’ minds as a discussion point for routinely using carb heat on every approach in every carbureted airplane (with technical exceptions, of course). — A 2°C temperature-dewpoint spread at the surface implies a broken cloud layer possible 1000’ above the field, about at pattern altitude; 88% saturation might be 98% on downwind. — Side note: Continental powered Cessnas tended to ice much easier and dramatically. Love the airplanes but CFIs? Beat that carb heat discipline in! It only takes once for carb heat insufficiency to result in a hull loss (and d*ath).