Individually Owned: 150,657
Corporate Owned: 137,281
Phoenix Regional Airport
Aircraft Accident/Incident Report
Casa Grande, Arizona 85222
Wednesday, February 5, 2003 8:15 MST
NTSB Narrative Summary Released at Completion of Accident
The helicopter made a hard landing following a failure of the antitorque system. While in the landing pattern, the student and CFI heard a "bang." The CFI took the flight controls, initiated an autorotation, and turned to an open area for an emergency landing. During the autorotation the CFI noticed a loss of his ability to maintain directional control. He lowered the collective and continued with the autorotation. As he pulled collective to cushion the landing the helicopter yawed to the left, landed firmly on the ground, and rolled over on to its right side. The CFI's execution of an autorotative landing failed to adjust for the engagement of the engine when he pulled in collective to cushion the landing. Engagement of engine power in the autorotative flare caused the helicopter to yaw left, which was not compensated for by the failed tail rotor. The helicopter encountered ground resistance when it landed, and the force of the uncontrolled left yaw rolled it over onto its right side. The FAA Rotorcraft Flying Handbook describes the appropriate response to an antitorque failure as an entry into an autorotation profile by reducing the collective and rolling off the throttle. Rolling off the throttle will prevent the engine from engaging during the autorotative landing. The manufacturer's flight manual does not address the issue of performing an autorotative landing with a tail rotor failure. Examination of the helicopter revealed that the secondary drive shaft appeared to have fractured between the lower bearing and the lock collar. Examination of the shaft revealed fretting and corrosion in the area contacted by the lock collar. The fracture was a result of fatigue cracking that initiated in the area of fretting and corrosion. This secondary drive shaft had been involved in one helicopter rollover and two tail rotor strikes. It is possible that excessive loads generated during these previous events was sufficient to loosen the lower bearing on the shaft and initiate the fretting and corrosion process that eventually led to the initiation of a fatigue crack.
NTSB Probable Cause Narrative
the flight instructor's failure to maintain directional control of the helicopter during the flare and landing. Factors in the accident were the failure of the secondary drive shaft and inadequate tail rotor failure procedures specified by the manufacturer.
Event Information
| Type of Event | Accident |
| Event Date | 2/5/2003 |
| Event Day of the Week | Wednesday |
| Time of Event | 815 |
| Event Time Zone | Mountain Standard Time |
| Event City | Casa Grande |
| Event State | ARIZONA |
| Event Country | -- |
| Zipcode of the event site | 85222 |
| Event Date Year | 2003 |
| Event Date Month | 2 |
| MidAir Collision Indicator | No |
| On Ground Collision occurred ? | No |
| Event Location Latitude | 325950N |
| Event Location Longitude | 1115523W |
| Event Location Airport | Phoenix Regional |
| Event Location Nearest Airport ID | A39 |
| Indicates whether the acc/inc occurred off or on an airport | On Airport |
| Distance from airport in statute miles | -- |
| Degrees magnetic from airport | -- |
| Airport Elevation | 1300 |
| Weather Briefing Completeness | Not pertinent |
| Investigator's weather source | Weather Observation Facility |
| Time of the weather observation | 745 Mountain Standard Time |
| Direction of event from weather observation facility (degrees) | 340 |
| Weather Observation Facility ID | CHD |
| Elevation of weather observation facility | 1243 |
| Distance of event from weather observation facility (units?) | 19 |
| Time Zone of the weather observation | MST |
| Lighting Conditions | Day |
| Lowest Ceiling Height | 25000 |
| Lowest Non-Ceiling Height | -- |
| Sky/Lowest/Cloud Conditions | Clear |
| Sky Condition for Lowest Ceiling | Broken |
| Visibility Runway Visual Range (Feet) | -- |
| Visibility Runway Visual Value (Statute Miles) | -- |
| Visibility (Statute Miles) | 10 |
| Air Temperature at event time (in degrees celsius) | 16 |
| Dew Point at event time (in degress fahrenheit) | 4 |
| Wind Direction (degrees magnetic) | 90 |
| Variable Wind Indicator | Wind direction could be determined |
| Wind Speed (knots) | 5 |
| Wind Velocity Indicator | -- |
| Wind Gust Indicator | Gusting |
| Wind Gust (knots) | 0 |
| Altimeter Setting at event time (in. Hg) | 30.1 |
| Density Altitude (feet) | -- |
| Intensity of Precipitation | -- |
| METAR weather report | -- |
| Event Highest Injury | Minor |
| On Ground, Fatal Injuries | -- |
| On Ground, Minor Injuries | -- |
| On Ground, Serious Injuries | -- |
| Injury Total Fatal | -- |
| Injury Total Minor | 2 |
| Injury Total None | -- |
| Injury Total Serious | -- |
| Injury Total All | 2 |
| Investigating Agency | NTSB |
| NTSB Docket Number (internal use) | 16909 |
| NTSB Notification Source | FAA |
| NTSB Notification Date | Feb 5 2003 12:00AM |
| NTSB Notification Time | 1530 |
| Fiche Number and/or location -used to find docket information | DMS |
| Date of most recent change to record | Dec 28 2004 12:45PM |
| User who most recently changed record | NTSB\JOHB |
| Basic weather conditions | Visual Meteorological Cond |
| FAA District Office | WP-SDL-FSDO |
Aircraft Involved |
|
|---|---|
Aircraft #1 |
|
| Aircraft Registration Number | N9876D |
| NTSB Number | LAX03LA084 |
| Missing Aircraft Indicator | -- |
| Federal Aviation Reg. Part | Part 91: General Aviation |
| Type of Flight Plan filed | None |
| Flight plan Was Activated? | No |
| Damage | Substantial |
| Aircraft Fire | None |
| Aircraft Explosion | None |
| Aircraft Manufacturer's Full Name | Cobb International |
| Aircraft Model | Rotorway Exec 90 |
| Aircraft Series Identifier | -- |
| Aircraft Serial Number | 5160 |
| Certified Max Gross Weight | 1425 |
| Aircraft Category | Helicopter |
| Aircraft Registration Class | U.S. Registered/U.S. Soil |
| Aircraft is a homebuilt? | No |
| Flight Crew Seats | -- |
| Cabin Crew Seats | -- |
| Passenger Seats | -- |
| Total number of seats on the aircraft | 2 |
| Number of Engines | 1 |
| Fixed gear or retractable gear | Fixed |
| Aircraft, Type of Last Inspection | Continuous Airworthiness |
| Date of Last Inspection | Dec 3 2002 12:00AM |
| Airframe hours since last inspection | 12 |
| Airframe Hours | 364 |
| ELT Installed | Yes |
| ELT Activated | Unknown |
| ELT Aided Location of Event Site | Unknown |
| ELT Type | -- |
| Aircraft Owner Name | Cobb International Inc |
| Aircraft Owner Street Address | 4140 W. Mercury Way |
| Aircraft Owner City | Chandler |
| Aircraft Owner State | AZ |
| Aircraft Owner Country | USA |
| Aircraft Owner Zipcode | 85226 |
| Operator is an individual? | No |
| Operator Name | -- |
| Operator Same as Owner? | Yes |
| Operator Is Doing Business As | -- |
| Operator Address Same as Owner? | Yes |
| Operator Street Address | -- |
| Operator City | -- |
| Operator State | -- |
| Operator Country | -- |
| Operator Zip code | -- |
| Operator Code | -- |
| Owner has at least one certificate | None |
| Other Operator of large aircraft? | -- |
| Certified for Part 133 or 137 Operation | -- |
| Operator Certificate Number | -- |
| Indicates whether an air carrier operation was scheduled or not | -- |
| Indicates Domestic or International Flight | -- |
| Operator carrying Pax/Cargo/Mail | -- |
| Type of Flying (Per_Bus / Primary) | Instructional |
| Second Pilot on Board | Yes |
| Departure Point Same as Event | No |
| Departure Airport Code | P19 |
| Departure City | Chandler |
| Departure State | AZ |
| Departure Country | USA |
| Departure Time | 755 |
| Departure Time Zone | MST |
| Destination Same as Local Flt | crash at destination city |
| Destination Airport Code | A39 |
| Destination City | Casa Grande |
| Destination State | AZ |
| Destination Country | USA |
| Specific Phase of Flight | Approach - VFR pattern - base leg/base to final |
| Report sent to ICAO? | No |
| Evacuation occurred | No |
| Date of most recent change to record | Nov 8 2004 5:11PM |
| User who most recently changed record | COOS |
| Since inspection or accident | Time of Accident |
| Event Location Runway Number and Location | 03 |
| Runway Length | 4000 |
| Runway Width | 50 |
| Sight Seeing flight | No |
| Air Medical Flight | No |
| Medical Flight | -- |