Covering form of preliminary or final report
| Date of event : | 2019-05-27 |
| Incident number : | CZ-19-0347 |
| Report : | Final report |
| Place of event : | Letnany Airfield |
| Registration mark : | Accident |
| Weight category MTOM: : | <2250 kg |
| Type of operation : | Recreational and sport aviation |
| Plane / SFM : | Airplanes |
| Type of plane / SFM : | Cessna 152 |
| Health effects of event : | With injury |
| PDF document : | 
|
Description:
SUMMARY
Overview
On 27 May 2019, an air accident of the Cessna 152 aircraft, registration mark OK-KAL, took place in the vicinity of LKLT. The aircraft crashed into the rape field beyond the border of the Letňany Airport, close to the underground station, when attempting emergency landing. The aircraft engine lost power output during take-off shortly after lift-off. That is why the pilot carried out emergency landing in the field of full grown oil seed rape. Once the aircraft undercarriage touched the rape plants, the aircraft overturned. The pilot suffered a minor injury and the aircraft sustained substantial damage in the air accident.
Factual Information
On 27 May 2019, the pilot planned to fly from the Letňany Airport (LKLT) via Mníšek pod Brdy to the Plasy Airport (LKPS) and return back to the Letňany Airport (LKLT). When he arrived at LKLT, he conducted preparation of the aircraft and refuelled the tank with 27 l of fuel. The total amount of fuel was 72 l. The oil level was normal. The pilot inspected the aircraft exterior and found no defects.
After starting-up the engine, he requested taxiing clearance from TWR. At the holding position for take-off from RWY 23L, he was waiting for oil reaching the operating temperature. He performed the engine test. Following communication between LKLT AFIS and LKKB TWR, the pilot received instructions for departure. According to the instructions, he was supposed to take off from RWY 23L, make a left turn to the ROMEO point (SW of Říčany), and switch to the 120.880 MHz frequency. Afterwards, the pilot obtained clearance to enter RWY 23L. Having finished tasks before take-off, the pilot started taking off at 11:41. The aircraft lifted off at a speed of 50 kt. During acceleration after unstick, the aircraft accelerated to approx. 60–65 kt and flew over approx. ¾ of the runway length. The aircraft stopped accelerating and as it was going from acceleration to climb, the engine run began to be uneven and power output was lost. Having lost the engine power output, the pilot decided to land on a field that was slightly to the left of the take-off direction. For the lack of time, he did not manage to declare the state of emergency. The field selected for emergency landing was covered with full-grown rape approx. 1.3 m tall. The pilot was landing on top of the growth. Prior to flare, he managed to extend the flaps to 30 degrees. The aircraft landed on main undercarriage at the speed of some 50 kt. Upon the contact of the nose undercarriage with the high rape plant field growth, it overturned during sharp braking of the aircraft.
Analysis
The weather was suitable for the flight performance and no dangerous meteorological phenomena occurred at the given location.
The aircraft pilot held the necessary qualification, and had considerable piloting experience with the said type of powered glider. The pilot was medically fit to fly. Alcohol testing yielded a negative result.
The working fluids were of the required quality and were supplied in the correct and sufficient quantities. Working fluids had no effect on the occurrence of the event.
The take-off weight and the centre of gravity were within the permitted limits and had no impact on the occurrence of the event.
The maintenance and operation of the aircraft had been performed in accordance with the manufacturer’s requirements. The aircraft had not been showing any signs of defect until the event flight, it was operating and airworthy.
The aircraft was damaged beyond repair in the accident. The lower front of the fuselage (engine hood) was deformed. The upper tubular struts of the engine bed were bent while the lower tubular struts were broken. During the aircraft turnover, a strong impact of the vertical tail unit into the terrain occurred. The said impact caused deformation of the upper part of the vertical tail unit and damage to the force nodes of the connection with the horizontal tail units.
Due to the fact that no damage or obvious defects were found on the engine, it was decided to perform a practical inspection testing of the engine. The engine was reinstalled from the aircraft with registration mark “OK-KAL” into the aircraft with registration mark “OK-LTC” and on 31 May 2019, a control engine test was performed. The engine test proved the engine running smoothly and that it had sufficient power output. The only remaining possibility was a loss of power output due to the limited fuel supply that could be caused by the not fully open position of the fuel cock. Therefore, several simulations were performed with the fuel cock set in different positions.
These simulations resulted in the incomplete opening of the fuel cock as the most likely cause of the loss of engine power output. In this simulation, after about 25 s after setting the maximum power output, there was an immediate decrease to 1,000–1,500 RPM, power output decreased, and engine run became uneven. It follows that the fuel cock was probably in an intermediate position at take-off.
The only cause of the engine power output loss was the insufficient fuel supply to the engine. During the ground verification checks of the engine operation and simulation of insufficient fuel supply by closing the fuel cock, the loss of power output and engine performance were the same as during the event flight according to the pilot’s statement.
Causes
The cause of the accident was a loss of engine power output during take-off caused by insufficient fuel supplied to the engine, probably due to insufficiently open fuel cock.
Attached final report in PDF file is in original Czech language.