# NTSB LAX98LA242: Enstrom F28A, N288Q, Pleasanton, CA, July 24, 1998 - Type: NTSB accident investigation - Classification: Accident · No injuries · Limited investigation · Final report - Date: July 23, 1998, 19:00 local (Jul 24, 1998, 02:00 UTC) - Place: Pleasanton, CA - Coordinates: 37.679061, -121.749252 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=37.6791&lon=-121.7493&mi=10 - Phase of flight: [Landing](https://openairdocs.org/ntsb-phases/550) (OpenAirDocs' grouping) - Highest injury: No injuries - Injuries: 2 uninjured - Status: Completed, report March 30, 2000 - Report: Approved by Office Director - NTSB case key (mKey): 43554 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=LAX98LA242 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/43554/pdf - Page: https://openairdocs.org/ntsb/LAX98LA242 ## Probable cause The flight instructor's delayed remedial action and the student pilot's failure to maintain rotor RPM. A factor was the downhill terrain. ## Sequence of events In NTSB's coding before 2008 (https://www.ntsb.gov/GILS/Documents/codman.pdf). - On ground/water encounter with terrain/water, landing - flare/touchdown - terrain condition - downhill (contributing factor) - remedial action - delayed, pilot in command(cfi) (cause) - rotor rpm - not maintained, dual student (cause) ## Analysis The dual student performed an off-airport pinnacle landing. The CFI stated that the helicopter began to vibrate and moved sideways so he rolled on power. By the time the helicopter reached the edge of the landing area, the rpm had decreased and he could not reposition the aircraft. The CFI reported that he pedal-turned so that the tail was pointing downhill, lowered the collective, and rolled off the throttle. The helicopter slid approximately 300 feet off the top of the hill and down a 30-degree slope. The main rotor blades contacted the ground but the aircraft remained upright. The CFI reported that there were no mechanical malfunctions with the aircraft prior to the accident. ## Factual narrative On July 23, 1998, at 1900 hours Pacific daylight time, an Enstrom F28A, N288Q, overshot the intended landing area and slid down a 30-degree hillside near Pleasanton, California. The aircraft sustained substantial damage. The certified flight instructor and dual student/owner, the sole occupants, were not injured. The local instructional flight last departed the Reid-Hillview Airport in San Jose, California, at 1830, and was en route to Livermore, California. Visual meteorological conditions prevailed and no flight plan was filed. The certified flight instructor (CFI) reported that he and the student were practicing off-airport landings. The student performed a pinnacle approach and landing. The CFI stated that the helicopter started to vibrate and move sideways so he rolled on power. By the time the helicopter reached the edge of the landing area, the rpm had decreased. The CFI reported that he was not able to reposition the helicopter to a higher area, so he pedal-turned to put the tail downhill, lowered the collective, and rolled off the throttle. The helicopter slid approximately 300 feet off the top of the hill and down a 30-degree slope. The main rotor blades contacted the ground but the aircraft remained upright. The CFI reported that there were no mechanical malfunctions with the aircraft prior to the accident. ## Aircraft - Registration: [N288Q](https://openairdocs.org/deregistered/N288Q-2001-09-19), registration cancelled 2001-09-19, S/N 298 (OpenAirDocs) - Reported make and model: Enstrom F28A - Registry model: [Enstrom F-28A](https://openairdocs.org/model/enstrom-f-28a) (registry code 3300406) (OpenAirDocs) - Category: Helicopter - Serial number: 298 - Airframe hours: 1088 - Engines: Lycoming HIO-360-CIA 205 horsepower reciprocating - Damage: Substantial damage - Flight: Instructional, Part 91 - Operator: William Mohler, doing business as Los Gatos Construction Co. Inc - Registered owner: Los Gatos Construction Co. Inc - Airworthiness certificate: Standard, Normal - Last inspection: Annual, May 4, 1997, 3 hours before - Departed: RHV, SAN JOSE, CA - Destination: LVK, LIVERMORE, CA ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 59; airline transport, commercial; airplane ratings: single-engine land, single-engine sea, multi-engine land; instrument ratings: helicopter; medical: class 2, valid medical--w/ waivers/lim; seat: left; flight hours: 5,885 total, 36 in this make and model, 2,465 as pilot in command, 40 in the last 90 days, 13 in the last 30 days, 2 in the last 24 hours ## Weather - Conditions: Visual (VMC), Day - Wind: 280° at 13 knots - Visibility: 10 statute miles - Lowest ceiling: none - Temperature: 72 °F, dew point 57 °F - Altimeter: 29.00 inHg - Observed at: LVK ## 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 19980723017639A](https://openairdocs.org/incident/19980723017639A), Jul 23, 1998: Enstrm F28A, Pleasanton, CA, Substantial damage. (.4)The dual student performed an off-airport pinnacle landing. The CFI stated that the helicopter began to vibrate and moved sideways so he rolled on power.… 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.