# NTSB MIA94GA072: Robinson R-22B, N591PD, Pompano Beach, FL, February 14, 1994 - Type: NTSB accident investigation - Classification: Accident · Minor injuries · Final report - Date: February 14, 1994, 15:20 local (20:20 UTC) - Place: Pompano Beach, FL - Location: 26.2368° N, 80.1221° W: Placed by OpenAirDocs from NTSB’s distance and direction from POMPANO BEACH AIRPARK (PMP), within about a mile (OpenAirDocs) - Nearby events: https://openairdocs.org/map.md?lat=26.2368&lon=-80.1221&mi=10 - Phase of flight: [Approach](https://openairdocs.org/ntsb-phases/500) (OpenAirDocs' grouping) - Highest injury: Minor injuries - Injuries: 1 minor, 1 uninjured - Status: Completed, report November 18, 1994 - Report: Approved by Office Director - NTSB case key (mKey): 37435 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=MIA94GA072 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/37435/pdf - Page: https://openairdocs.org/ntsb/MIA94GA072 ## Probable cause FAILURE OF THE PILOT-IN-COMMAND TO USE CARBURETOR HEAT DURING A POWEROFF AUTOROTATION, RESULTING IN THE ENGINE NOT RESPONDING TO THROTTLE INPUT DURING RECOVERY DUE TO CARBURETOR ICE BUILDUP. ## Sequence of events In NTSB's coding before 2008 (https://www.ntsb.gov/GILS/Documents/codman.pdf). - Loss of engine power, approach - weather condition - carburetor icing conditions (contributing factor) - carburetor heat - not used, pilot in command (cause) - fuel system,carburetor - ice - Hard landing, descent ## Analysis Both pilots stated they were performing their third 180-degree autorotation with power recovery. They were not using the carburetor heat. They heard the engine running as they began the recovery but the engine did not respond to throttle input. The helicopter touched down hard and the main rotor blades contacted the tail boom and severed it and the tail rotor. The helicopter spun to the left several times and the right skid collapsed before the helicopter came to rest upright. After the accident the engine was operated in the helicopter and also in a test cell with no evidence to indicate failure or malfunction. At the time of the accident the helicopter was operating in conditions conducive to serious carburetor icing at glide power. The flight manual for the helicopter requires use of carburetor heat when operating in conditions conducive to carburetor icing. ## Factual narrative On February 14, 1994, at 1520 eastern standard time, a Robinson R22 Beta, N591PD, registered to the City of Fort Lauderdale, landed hard at Pompano Beach Airpark, Pompano Beach, Florida, following loss of engine power during recovery from a autorotation landing. The flight was a 14 CFR Part 91, public-use flight. Visual meteorological conditions prevailed at the time and no flight plan was filed. The aircraft received substantial damage and the airline transport-rated flight instructor was not injured. The commercial-rated dual student received minor injuries. The flight originated at Fort Lauderdale, Florida, on February 14, 1994, about 1445. Both pilots stated the instructor pilot was demonstrating a 180-degree autorotation with power recovery. The dual student was following on the flight controls. They had completed two previous autorotations. As they flared at the completion of the autorotation they heard the engine running at idle; however, when they applied power to recover, the engine did not respond. The helicopter touched down hard and the main rotor blades severed part of the tailboom and the tail rotor. The helicopter spun to the left several rotations and the right skid collapsed. The helicopter came to rest upright, leaning to the right. They stated the engine was at idle power for about 30 to 40 seconds during each autorotation and that they were not applying carburetor heat. After the accident the main rotor blades were removed and the tail rotor drive was disconnected from the transmission. The engine was started and operated to 3,000 rpm where it ran rough and popped. A magneto check was performed and the right magneto had over a 200 rpm drop. The left mag had a normal drop. The no. 2 cylinder bottom plug, which operates off the right magneto, was found to be fouled by oil and the ignition lead was not firing. All cylinders developed normal compression. The engine was removed from the helicopter and the exhaust valve guide clearance was measured. The nos. 1, 2, and 4 exhaust valve guides were found worn beyond maximum limits. No 3 cylinder exhaust valve guide was at maximum limit. The engine was placed in a test cell and operated to maximum power with no evidence of failure or malfunction. During initial running the carburetor fuel shutoff needle valve stuck partially open. This corrected itself shortly after start of the engine run. The no. two cylinder bottom spark lead from the right magneto operated normally during this test run. A review of carburetor icing probability curves indicate that for the conditions present at the time of the accident, temperature 72 degrees F and dewpoint temperature 55 degrees F, the helicopter was operating in conditions conducive to serious icing at glide power. The FAA approved flight manual for the Robinson R22 states " when conditions conducive to carburetor ice are known or suspected, such as fog, rain, high humidity, or when operating near water, use carb heat as follows: during autorotation or reduced power below 18 inches MP apply full Carb Heat regardless of CAT gage temperature." See attached icing probability curves and pages from the Robinson Flight Manual. ## Aircraft - Registration: [N591PD](https://openairdocs.org/deregistered/N591PD-1994-08-05), registration cancelled 1994-08-05, S/N 0592 (OpenAirDocs) - Reported make and model: ROBINSON R-22B - Registry model: [Robinson Helicopter R22 BETA](https://openairdocs.org/model/robinson-helicopter-r22-beta) (registry code 7640110) (OpenAirDocs) - Category: Helicopter - Serial number: 592 - Airframe hours: 7073 - Engines: LYCOMING O-320-B2C 160 horsepower reciprocating - Damage: Substantial damage - Flight: Public aircraft, Part 91 - Registered owner: City Of Ft. Lauderdale - Airworthiness certificate: Standard, Normal - Last inspection: 100 hour, January 20, 1994, 73 hours before - Departed: FXE, FORT LAUDERDALE, FL - Airport: PMP, Pompano Beach Airpark, runway 5, 4,001 × 150 ft, asphalt ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 53; airline transport, flight instructor; airplane ratings: multi-engine land, single-engine land, single-engine sea; instrument ratings: airplane, helicopter; medical: class 1, valid medical--no waivers/lim.; seat: left; flight hours: 16,200 total, 4,100 in this make and model, 15,300 as pilot in command, 50 in the last 90 days, 15 in the last 30 days, 1 in the last 24 hours ## Weather - Conditions: Visual (VMC), Day - Wind: 30° at 18 knots - Visibility: 9 statute miles - Lowest ceiling: 2,000 ft overcast - Temperature: 72 °F, dew point 55 °F - Altimeter: 30.00 inHg - Observed at: PMP, 1 nm away ## FAA reports on this event (1) The FAA's own accident and incident reports, matched to the aircraft by N-number and date (OpenAirDocs). - [Accident 19940214048959A](https://openairdocs.org/incident/19940214048959A), Feb 14, 1994: Robsin R22BETA, Pompano Beach, FL, Substantial damage. Engine quit on recovery from autorotation public use dual. Landed hard. Chopped tailboom. Carb ice. Worn engine. From the NTSB's public API. Aircraft are matched to registry aircraft by N-number and event date, checked against the reported serial number, make and model; the registry's history has gaps, so older matches can be wrong. Compare the reported make and model. --- OpenAirDocs.org is an independent research project of [Contrail Labs](https://contraillabs.com/). It is not affiliated with the FAA or the NTSB. Source documents are U.S. government works in the public domain.