# NTSB LAX94LA069: Rotorway EXEC-90, N89678, Chandler, AZ, December 8, 1993 - Type: NTSB accident investigation - Classification: Accident · Minor injuries · Limited investigation · Final report - Date: December 8, 1993, 08:00 local (15:00 UTC) - Place: Chandler, AZ - Coordinates: 33.319171, -111.869117 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=33.3192&lon=-111.8691&mi=10 - Phase of flight: [Initial climb](https://openairdocs.org/ntsb-phases/350) (OpenAirDocs' grouping) - Highest injury: Minor injuries - Injuries: 2 minor - Status: Completed, report September 13, 1994 - Report: Approved by Office Director - NTSB case key (mKey): 28618 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=LAX94LA069 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/28618/pdf - Page: https://openairdocs.org/ntsb/LAX94LA069 ## Probable cause THE FLIGHT INSTRUCTOR'S FAILURE TO PROPERLY FOLLOW THE AIRCRAFT BALLASTING PROCEDURES THAT RESULTED IN A LOSS OF CONTROL WHEN THE HELICOPTER'S CENTER OF GRAVITY LIMITS WERE EXCEEDED. INADEQUATE SUPERVISION OF THE TRAINING FLIGHT WAS A FACTOR IN THE ACCIDENT. ## Sequence of events In NTSB's coding before 2008 (https://www.ntsb.gov/GILS/Documents/codman.pdf). - Loss of control - in flight, takeoff - initial climb - procedures/directives - not followed, pilot in command(cfi) (cause) - supervision - inadequate, pilot in command(cfi) (contributing factor) - aircraft weight and balance - exceeded, pilot in command(cfi) (cause) - aircraft control - not possible, pilot in command(cfi) - Hard landing, descent - uncontrolled - Roll over, landing - flare/touchdown ## Analysis A FLIGHT INSTRUCTOR WAS PROVIDING HELICOPTER INSTRUCTION TO A SECOND PILOT IN AN EXPERIMENTAL AIRCRAFT. A MOVEABLE BALLAST WEIGHT IS UTILIZED ON THE HELICOPTER TO ASSURE THAT THE CENTER OF GRAVITY LIMITS ARE NOT EXCEEDED. THE BALLAST WEIGHT IS POSITIONED ALONG THE CENTERLINE OF THE AIRCRAFT WHEN IT IS OCCUPIED BY TWO PERSONS. THE WEIGHT IS POSITIONED ON THE RIGHT LANDING GEAR SKID TUBE WHEN THE HELICOPTER IS OCCUPIED BY ONLY ONE PERSON. AFTER COMPLETING SOLO HOVER MANEUVERS, THE INSTRUCTOR BOARDED THE HELICOPTER AND INSTRUCTED THE STUDENT TO FLY BACK TO A COMPANY BUILDING. THE BALLAST WEIGHT WAS STILL POSITIONED ON THE RIGHT SKID. AFTER TAKEOFF WITH THE TWO OCCUPANTS, THE HELICOPTER PITCHED NOSE DOWN. THE NOSE AND MAIN ROTOR BLADES STRUCK THE GROUND AND THE HELICOPTER ROLLED OVER. ## Factual narrative On December 8, 1993, at 0800 hours mountain standard time, an experimental Rotorway Exec-90 helicopter, N89678, crashed during takeoff at Stellar Airpark, Chandler, Arizona. The pilots were conducting a local visual flight rules (VFR) instructional flight. The helicopter, operated by Rotorway Aircraft Inc., Chandler, Arizona, sustained substantial damage. The certificated commercial pilot/certified flight instructor (first pilot), and the certificated private pilot/dual student (second pilot), received minor injuries. Visual meteorological conditions prevailed. The helicopter is equipped with a moveable ballast weight. When the helicopter is occupied by two pilots, the weight must be placed in an aft, stowed position along the longitudinal axis of the aircraft. When the helicopter is occupied by one pilot, the ballast weight is positioned on the front portion of the right landing gear skid tube. The proper positioning of the ballast weight is required to ensure that the helicopter's center of gravity (CG) limits are not exceeded. The first pilot reported that he was providing helicopter instruction to the second pilot on a taxiway at the south end of the airport. The first pilot positioned the ballast weight on the right skid tube and the second pilot began practicing solo hovering maneuvers. The first pilot then boarded the helicopter for a verbal critique, and then requested that the second pilot fly back to the company building. After takeoff, the helicopter pitched forward and the first pilot attempted to gain control of the aircraft by holding full aft cyclic pressure. The nose of the helicopter and the main rotor blades contacted the ground. The helicopter then rolled over onto its left side. An airworthiness inspector, Federal Aviation Administration, Flight Standards District Office, Scottsdale, Arizona, reported that the ballast weight was improperly positioned on the right skid of the helicopter that is normally utilized when the helicopter is flown by one pilot. The first pilot holds a commercial pilot certificate with airplane single-engine land, rotorcraft helicopter, and instrument airplane ratings. In addition, the first pilot is a certificated flight instructor with a rotorcraft helicopter rating. The most recent second-class medical certificate was issued to the pilot on April 8, 1992, and contains the limitation that the pilot must wear correcting lenses for far vision. According to the pilot/operator report submitted by the pilot, his total aeronautical experience consists of 1,941.7 hours, of which 212.2 were accrued in the accident helicopter make and model. In the preceding 90 and 30 days prior to the accident, the report lists a total of 100.5 and 32.6 hours, respectively, flown. The second pilot holds a private pilot certificate with an airplane single-engine land rating. The most recent third-class medical certificate was issued to the pilot on December 1, 1992, and contains the limitation that the pilot must wear correcting lenses. The second pilot reported that his total aeronautical experience consists of 558.4 hours, of which 15.1 hours were accrued in the accident helicopter make and model. In the preceding 90 and 30 days prior to the accident, the report lists a total of 7.4 and 1.7 hours respectively flown in the accident aircraft. ## Aircraft - Registration: [N89678](https://openairdocs.org/deregistered/N89678-2001-06-26), registration cancelled 2001-06-26, S/N R.I. 5026 (OpenAirDocs) - Reported make and model: ROTORWAY EXEC-90 - Registry model: [Cobb Intl Inc DBA Rotorway INT ROTORWAY EXEC 90](https://openairdocs.org/model/cobb-intl-inc-dba-rotorway-int-rotorway-exec-90) (registry code 13017LM) (OpenAirDocs) - Category: Helicopter, amateur-built - Serial number: RI-5023 - Airframe hours: 217 - Engines: ROTORWAY R-162 125 horsepower reciprocating - Damage: Substantial damage - Flight: Instructional, Part 91 - Operator: Cobb International Inc., doing business as Rotorway Aircraft Inc. - Registered owner: Cobb International - Airworthiness certificate: Special, Experimental (Special) - Last inspection: Continuous airworthiness, March 31, 1993, 217 hours before - Airport: P19, Stellar Airpark ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 45; flight instructor, commercial; airplane ratings: single-engine land; instrument ratings: airplane; medical: class 2, valid medical--w/ waivers/lim; seat: right; flight hours: 1,942 total, 212 in this make and model, 1,719 as pilot in command, 101 in the last 90 days, 33 in the last 30 days, 3 in the last 24 hours ## Weather - Conditions: Visual (VMC), Day - Wind: 120° at 5 knots - Visibility: 45 statute miles - Lowest ceiling: 25,000 ft broken - Temperature: 54 °F, dew point 30 °F - Altimeter: 30.00 inHg - Observed at: PHX, 10 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 19931208046329A](https://openairdocs.org/incident/19931208046329A), Dec 8, 1993: Amtr ROTORWAYEXEC, Chandler, AZ, Substantial damage. Balance ballast weight not switched to rear for 2 occupants. Was forward for student solo. Crashed nose down. ## Other investigations on N89678 (3) 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. - [NTSB LAX00LA071](https://openairdocs.org/ntsb/LAX00LA071), Jan 4, 2000: Rotorway Exec 90 (N89678), Chandler, AZ, substantial damage. Probable cause: the fatigue fracture and separation of the secondary drive shaft, which resulted from the manufacturer's inadequate quality control process. - [NTSB LAX96LA210](https://openairdocs.org/ntsb/LAX96LA210), May 22, 1996: Rotorway Exec 9 (N89678), Chandler, AZ, substantial damage. Probable cause: a loss of engine power due to a failed piston and piston ring in a critical phase of flight. - [NTSB LAX93LA111](https://openairdocs.org/ntsb/LAX93LA111), Feb 9, 1993: Cobb Intl Exec 90 (N89678), Chandler, AZ, substantial damage. Probable cause: THE MANUFACTURER'S INADEQUATE QUALITY CONTROL WHICH RESULTED IN THE FATIGUE OF THE VALVE STEM. THE SOFT TERRAIN CONTRIBUTED TO THIS ACCIDENT. 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.