# NTSB LAX02LA294: Robinson R22B, N2331, Silverado, CA, September 23, 2002 - Type: NTSB accident investigation - Classification: Accident · No injuries · Limited investigation · Final report - Date: September 23, 2002, 10:00 local (17:00 UTC) - Place: Silverado, CA - Coordinates: 33.75, -117.566665 - Nearby events: https://openairdocs.org/map.md?lat=33.7500&lon=-117.5667&mi=10 - Phase of flight: [Maneuvering](https://openairdocs.org/ntsb-phases/450) (OpenAirDocs' grouping) - Highest injury: No injuries - Injuries: 2 uninjured - Status: Completed, report September 29, 2004 - Report: Approved by Office Director - Parties: Federal Aviation Administration - NTSB case key (mKey): 55762 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=LAX02LA294 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/55762/pdf - Page: https://openairdocs.org/ntsb/LAX02LA294 ## Probable cause The student's failure to maintain adequate main rotor rpm, and the flight instructor's inadequate supervision of the flight. Contributing factors were the hilly terrain and the relative high density altitude conditions. ## Sequence of events In NTSB's coding before 2008 (https://www.ntsb.gov/GILS/Documents/codman.pdf). - Loss of control - in flight, maneuvering - rotor rpm - not maintained, dual student (cause) - weather condition - high density altitude (contributing factor) - supervision - inadequate, pilot in command(cfi) (cause) - Forced landing, emergency descent/landing - In flight collision with terrain/water, emergency descent/landing - terrain condition - mountainous/hilly (contributing factor) ## Analysis During an instructional flight, a forced landing occurred on slopping terrain wherein the main rotor blades contacted the hillside and the tail boom was bent. The certified flight instructor (CFI) and student were operating the helicopter near its maximum certificated gross weight over a 2,900-foot mean sea level hillside, with a density altitude higher than 5,800 feet. The CFI failed to adequately monitor his student's handling of the controls, and the main rotor rpm decreased. Despite the CFI's subsequent efforts at regaining adequate rpm, the low rotor rpm condition continued, which necessitated a forced landing. ## Factual narrative On September 23, 2002, about 1000 Pacific daylight time, a Robinson R22B, N2331X, impacted hilly terrain during an off-airport forced landing about 4 miles east of Silverado, California. Neither the commercial pilot, who possessed a certificated flight instructor (CFI) certificate, nor the private pilot was injured during the instructional flight. The helicopter was substantially damaged. The helicopter was operated by Helistream, Inc., Santa Ana, California, under the provisions of 14 CFR Part 91. Visual meteorological conditions prevailed at the time, and no flight plan had been filed. The flight originated from Santa Ana about 0945. The operator's manager reported to the National Transportation Safety Board investigator that the CFI's student was, in part, practicing landings. During approach in a confined mountainous area, low main rotor rpm was experienced and the CFI took over the controls. The terrain elevation was about 2,900 feet mean sea level. Despite the CFI's efforts, he was not able to regain rotor rpm. The helicopter touched down on slopping terrain short of the intended helipad. During the touchdown sequence, the main rotor blades contacted the hillside, and the helicopter's fuselage yawed about 360 degrees before coming to rest in an upright attitude with a bent tail boom. In the CFI's completed accident report, he indicated that during the approach he heard the low rotor rpm horn. Immediately thereafter, he looked at the rotor rpm gauge and lowered the collective while rolling on the throttle. The CFI stated that the rpm did not increase. Then, he added a "large amount of throttle while (again) lowering the collective, but the rpm continued to steadily decrease." The CFI also indicated that in the vicinity of the accident site the outside air temperature was about 95 degrees Fahrenheit. The wind was calm. No mechanical malfunctions or failures were reported with the helicopter. Federal Aviation Administration airman certificate and medical documents dated July and August 2002, indicate that the CFI and the private pilot's combined weights were approximately 358 pounds. The CFI reported that 23 gallons of fuel were on board upon takeoff for the accident flight. The operator stated that the helicopter was flying near its maximum certificated gross weight. Based upon the atmospheric conditions provided by the CFI/operator, the density altitude was calculated to be in excess of 5,800 feet. ## Aircraft - Registration: N2331 (not matched to a registry record) - Reported make and model: Robinson R22B - Category: Helicopter - Serial number: 2145 - Airframe hours: 3788 - Engines: Lycoming O-320-B2C 131 horsepower reciprocating - Damage: Substantial damage - Flight: Instructional, Part 91 - Registered owner: Helistream, Inc. - Airworthiness certificate: Standard, Normal - Last inspection: Annual, September 5, 2002, 48 hours before - Departed: SNA, Santa Ana, CA - Destination: SNA, Santa Ana, CA ## Flight crew As NTSB recorded them. NTSB leaves out names. - Flight instructor; age 26; injuries: none; flight instructor, commercial; medical: class 2, valid medical--no waivers/lim.; last flight review July 24, 2002; seat: left; flight hours: 750 total, 700 in this make and model, 690 as pilot in command, 200 in the last 90 days, 70 in the last 30 days, 6 in the last 24 hours - Student pilot; age 23; injuries: none; private; medical: class 3, valid medical--w/ waivers/lim; last flight review August 1, 2002; seat: right; flight hours: 138 total, 28 in this make and model, 50 as pilot in command, 46 in the last 90 days, 30 in the last 30 days, 1 in the last 24 hours ## Weather - Conditions: Visual (VMC), Day - Wind: 300° at 3 knots - Visibility: 10 statute miles - Lowest ceiling: none - Temperature: 82 °F, dew point 48 °F - Altimeter: 29.87 inHg - Observed at: RAL, 14 nm away 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.