Individually Owned: 150,657
Corporate Owned: 137,281
Aircraft Accident/Incident Report
Westlake Villag, California 91359
Saturday, January 11, 2003 10:23 PST
NTSB Narrative Summary Released at Completion of Accident
The airplane collided with ground obstacles during a forced landing when the pilots could not maintain altitude after one propeller blade and part of the propeller hub from the right engine separated in flight. The CFI and the student practiced two simulated engine-out maneuvers. The CFI was reaching for the mixture control for a third simulation when he heard a loud bang. The airplane yawed violently to the right and began to lose altitude. The CFI turned toward his home field, but was having difficulty maintaining altitude. He decided that he would not be able to make it to the airport, and would have to make an off field landing. He landed in the only clear spot that he could see, which was a cemetery. The airplane collided with monuments and a wood chip pile before coming to rest next to a mausoleum. The right propeller hub fractured and separated. Investigators did not recover one blade and the corresponding part of the hub. The hub fractured as a result of fatigue cracking emanating from one of the grease-fitting holes. The fatigue cracking originated in the area of the grease-fitting threads closest to the interior surface of the hub, at the intersection between the grease-fitting hole and the chamfer. No material or manufacturing defect was found that could be identified as the source of the fatigue cracking. The fatigue cracking originated just outside the thread remnants of the grease fitting hole that were plastically deformed during a chamfering process. The grease fitting was located in a region where the wall of the hub was approximately at its thinnest, and where there was a slight change in the profile along the axis of the propeller. These geometrical factors would have led to high stresses at the edges of the hole. Chamfers were retrofitted to the grease-fitting holes by the manufacturer at both the interior and exterior surfaces of the hub in response to fatigue fractures that occurred in three-bladed propellers. This accident was the first occurrence of fatigue emanating from a grease-fitting hole for a two-bladed propeller. The chamfering was apparently introduced in an effort to smooth the stress distribution around the grease-fitting holes. The chamfer at the interior surface should have removed the stress concentration associated with the change in wall profile, but would also have decreased the amount of material in the wall, leading to higher stresses overall. The stress concentration associated with the grease-fitting hole and the chamfer, coupled with the location in a position where the hub wall was very thin, were likely sufficient to initiate fatigue cracking in this case. In more recently manufactured hubs, the grease-fitting holes have been relocated to positions where the hub wall is much thicker.
NTSB Probable Cause Narrative
a fatigue crack in the propeller hub due to the inadequate design location of the grease fitting and the chamfering process.
Event Information
| Type of Event | Accident |
| Event Date | 1/11/2003 |
| Event Day of the Week | Saturday |
| Time of Event | 1023 |
| Event Time Zone | Pacific Standard Time |
| Event City | Westlake Villag |
| Event State | CALIFORNIA |
| Event Country | -- |
| Zipcode of the event site | 91359 |
| Event Date Year | 2003 |
| Event Date Month | 1 |
| MidAir Collision Indicator | No |
| On Ground Collision occurred ? | No |
| Event Location Latitude | 340800N |
| Event Location Longitude | 1184300W |
| Event Location Airport | -- |
| Event Location Nearest Airport ID | -- |
| Indicates whether the acc/inc occurred off or on an airport | Off Airport/Airstrip |
| Distance from airport in statute miles | -- |
| Degrees magnetic from airport | -- |
| Airport Elevation | -- |
| Weather Briefing Completeness | Not pertinent |
| Investigator's weather source | Weather Observation Facility |
| Time of the weather observation | 958 Pacific Daylight Time |
| Direction of event from weather observation facility (degrees) | 60 |
| Weather Observation Facility ID | VNY |
| Elevation of weather observation facility | 802 |
| Distance of event from weather observation facility (units?) | 20 |
| Time Zone of the weather observation | PDT |
| Lighting Conditions | Day |
| Lowest Ceiling Height | -- |
| Lowest Non-Ceiling Height | 600 |
| Sky/Lowest/Cloud Conditions | Few |
| Sky Condition for Lowest Ceiling | None |
| Visibility Runway Visual Range (Feet) | -- |
| Visibility Runway Visual Value (Statute Miles) | -- |
| Visibility (Statute Miles) | 6 |
| Air Temperature at event time (in degrees celsius) | 11 |
| Dew Point at event time (in degress fahrenheit) | 8 |
| Wind Direction (degrees magnetic) | -- |
| Variable Wind Indicator | -- |
| Wind Speed (knots) | -- |
| Wind Velocity Indicator | Light and Variable |
| Wind Gust Indicator | Not Gusting |
| Wind Gust (knots) | -- |
| Altimeter Setting at event time (in. Hg) | 30.17 |
| Density Altitude (feet) | -- |
| Intensity of Precipitation | -- |
| METAR weather report | -- |
| Event Highest Injury | Serious |
| On Ground, Fatal Injuries | -- |
| On Ground, Minor Injuries | -- |
| On Ground, Serious Injuries | -- |
| Injury Total Fatal | -- |
| Injury Total Minor | -- |
| Injury Total None | -- |
| Injury Total Serious | 2 |
| Injury Total All | 2 |
| Investigating Agency | NTSB |
| NTSB Docket Number (internal use) | 17743 |
| NTSB Notification Source | FAA |
| NTSB Notification Date | Jan 11 2003 12:00AM |
| NTSB Notification Time | 1100 |
| Fiche Number and/or location -used to find docket information | DMS |
| Date of most recent change to record | Jun 8 2005 12:51PM |
| User who most recently changed record | NTSB\JOHB |
| Basic weather conditions | Visual Meteorological Cond |
| FAA District Office | WP-VNY-FSDO |
Aircraft Involved |
|
|---|---|
Aircraft #1 |
|
| Aircraft Registration Number | N56484 |
| NTSB Number | LAX03FA065 |
| Missing Aircraft Indicator | -- |
| Federal Aviation Reg. Part | Part 91: General Aviation |
| Type of Flight Plan filed | None |
| Flight plan Was Activated? | No |
| Damage | Destroyed |
| Aircraft Fire | None |
| Aircraft Explosion | None |
| Aircraft Manufacturer's Full Name | Piper |
| Aircraft Model | PA-34-200 |
| Aircraft Series Identifier | -- |
| Aircraft Serial Number | 34-7350338 |
| Certified Max Gross Weight | 4200 |
| Aircraft Category | Airplane |
| 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 | 6 |
| Number of Engines | 2 |
| Fixed gear or retractable gear | Retractable |
| Aircraft, Type of Last Inspection | 100 Hour |
| Date of Last Inspection | Nov 29 2002 12:00AM |
| Airframe hours since last inspection | 256 |
| Airframe Hours | -- |
| ELT Installed | Yes |
| ELT Activated | No |
| ELT Aided Location of Event Site | No |
| ELT Type | -- |
| Aircraft Owner Name | Roxy Corporation |
| Aircraft Owner Street Address | 3511 Silverside Rd, Suite 105 |
| Aircraft Owner City | Wilmington |
| Aircraft Owner State | DE |
| Aircraft Owner Country | USA |
| Aircraft Owner Zipcode | 19810 |
| Operator is an individual? | No |
| Operator Name | The Aero Club |
| Operator Same as Owner? | No |
| Operator Is Doing Business As | -- |
| Operator Address Same as Owner? | No |
| Operator Street Address | 7552 Hayvenhurst PL |
| Operator City | VAN NUYS |
| Operator State | CA |
| Operator Country | USA |
| Operator Zip code | 91406 |
| 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 | VNY |
| Departure City | Van Nuys |
| Departure State | CA |
| Departure Country | USA |
| Departure Time | 945 |
| Departure Time Zone | PST |
| Destination Same as Local Flt | dest & departure same, accident can occur anywhere |
| Destination Airport Code | -- |
| Destination City | -- |
| Destination State | -- |
| Destination Country | -- |
| Specific Phase of Flight | Maneuvering |
| Report sent to ICAO? | No |
| Evacuation occurred | No |
| Date of most recent change to record | Apr 6 2005 5:39PM |
| User who most recently changed record | COOS |
| Since inspection or accident | -- |
| Event Location Runway Number and Location | NA |
| Runway Length | -- |
| Runway Width | -- |
| Sight Seeing flight | No |
| Air Medical Flight | No |
| Medical Flight | -- |