# NTSB LAX93LA348: Robinson R22B, N47NH, Floriston, CA, September 10, 1993 - Type: NTSB accident investigation - Classification: Accident · Minor injuries · Limited investigation · Final report - Date: September 10, 1993, 12:40 local (19:40 UTC) - Place: Floriston, CA - Coordinates: 39.390037, -120.020248 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=39.3900&lon=-120.0202&mi=10 - Phase of flight: [Approach](https://openairdocs.org/ntsb-phases/500) (OpenAirDocs' grouping) - Highest injury: Minor injuries - Injuries: 2 minor - Status: Completed, report August 1, 1994 - Report: Approved by Office Director - NTSB case key (mKey): 28471 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=LAX93LA348 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/28471/pdf - Page: https://openairdocs.org/ntsb/LAX93LA348 ## Probable cause the flight instructor's failure to maintain main rotor RPM after initiating a go-around from a pinnacle approach. A factor in the accident was the high density altitude condition. ## Sequence of events In NTSB's coding before 2008 (https://www.ntsb.gov/GILS/Documents/codman.pdf). - In flight collision with terrain/water, go-around (vfr) - weather condition - high density altitude (contributing factor) - rotor rpm - not maintained, pilot in command(cfi) (cause) ## Analysis The CFI was instructing his student in performing pinnacle approaches and landings to high density altitude mountainous locations. The student was initially flying. When the R22 had descended to 50 feet above the 6,100 ft MSL pinnacle, the CFI elected to made a go-around after observing that the terrain was not appropriate for the landing. The CFI took control of the helicopter, began turning right, and observed that the main rotor RPM decreased. The CFI attempted to recover RPM by reducing collective and rolling on full throttle. The R22 continued descending until colliding with a tree and terrain. ## Factual narrative On September 10, 1993, at 1240 Pacific daylight time, a Robinson R22 Beta, N47NH, operated by Helicopter Adventures, Inc., Concord, California, descended into mountainous terrain during an instructional flight about 14 miles north of Floriston, California. Visual meteorological conditions prevailed at the time and the helicopter was substantially damaged. The flight instructor (CFI) and the student pilot received minor injuries. The flight originated from Reno, Nevada, on September 10, 1993, at 1145 PDT. On September 13, 1993, the CFI was interviewed via telephone. The CFI reported that during the flight lesson he planned to teach his student mountain flying techniques including how to perform "pinnacle landings." The CFI stated the student was initially flying the helicopter. However, during the pinnacle approach he took the controls to make a go-around because the landing site appeared to be unsatisfactory. The CFI further reported that at about 50 feet above ground level he turned the helicopter to the right toward lower elevation terrain. In the course of the turn, the main rotor RPM decayed and he lowered the collective. Rotor RPM was not restored and the helicopter descended into the mountainside. The CFI also stated that no mechanical problems were experienced during the flight. At the time of the accident, the helicopter's gross weight was about 1,290 pounds, the air temperature was 82 degrees Fahrenheit, and the pinnacle's elevation was about 6,100 feet mean sea level. In the CFI's completed "Aircraft Accident Report," NTSB Form 6120.1, he reported that during the attempted go-around "...the aircraft seemed to lose lift." According to the CFI, he rolled on full throttle; however, the helicopter continued descending until initially striking a tree about 50 feet above the ground at an airspeed of 40 knots. The CFI further indicated that, according to Robinson performance data, under certain conditions a R22 helicopter would have OUT and IN Ground Effect Hover Ceilings of 5,500 feet and 7,200 feet, respectively. ## Aircraft - Registration: [N47NH](https://openairdocs.org/deregistered/N47NH-2015-05-12), registration cancelled 2015-05-12, S/N 1192 (OpenAirDocs) - Reported make and model: ROBINSON R22B - Registry model: [Robinson Helicopter R22 BETA](https://openairdocs.org/model/robinson-helicopter-r22-beta) (registry code 7640110) (OpenAirDocs) - Category: Helicopter - Serial number: 1192 - Airframe hours: 3982 - Engines: LYCOMING O-320-B2C 160 horsepower reciprocating - Damage: Substantial damage - Flight: Instructional, Part 91 - Operator: Helicopter Adventures, Inc. - Registered owner: Charles William Aby Trust - Airworthiness certificate: Standard, Normal - Last inspection: Annual, August 31, 1993 - Departed: RNO, RENO, NV ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 23; flight instructor, commercial; airplane ratings: multi-engine land, single-engine land; instrument ratings: airplane, helicopter; medical: class 1, valid medical--no waivers/lim.; seat: left; flight hours: 1,225 total, 811 in this make and model, 1,113 as pilot in command, 163 in the last 90 days, 55 in the last 30 days, 5 in the last 24 hours ## Weather - Conditions: Visual (VMC), Day - Wind: 225° at 5 knots - Visibility: 30 statute miles - Lowest ceiling: 9,000 ft broken - Temperature: 82 °F, dew point 39 °F - Altimeter: 30.00 inHg ## 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 19930910033889A](https://openairdocs.org/incident/19930910033889A), Sep 10, 1993: Robsin R22BETA, Floriston, CA, Substantial damage. During pinnicle landing demo. Began go around. Rotor RPM decayed. Turned away but descended into trees on mountain. 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.