Individually Owned: 151,845
Corporate Owned: 143,699
Aircraft Accident/Incident Report
Farmingdale, New York 11735
Sunday, September 11, 1994 11:11 EDT
NTSB Narrative Summary Released at Completion of Accident
AFTER ABOUT 40 MINUTES OF FLIGHT, THE AIRSHIP CREW NOTED THE ENVELOPE PRESSURE BEGAN TO DROP. THEY TURNED BACK TO THE AIRPORT & DROPPED 300 LITERS OF WATER BALLAST 'PER THE FLIGHT MANUAL.' AT ABOUT 700'AGL & 2 MILES FROM THE AIRPORT, WITH THE PRESSURE LESS THAN 15MM, THE CREW REALIZED THEY WOULD NOT REACH THE AIRPORT. THE AIRSHIP WENT INTO A NOSE LOW ATTITUDE & WOULD NO LONGER MAINTAIN ALTITUDE. THE CREW SHUT DOWN THE ENGINES & ELECTRIC SYSTEM & LANDED IN A STREET, BUT THE GONDOLA & FORWARD PART OF THE ENVELOPE WERE DAMAGED. INVESTIGATION REVEALED THE CENTER DAMPER VALVE WAS OPEN. THERE WAS EVIDENCE THAT DURING FLIGHT, THE OPEN VALVE ALLOWED THE FORE & AFT BALLONETS TO EMPTY & THE CENTER BALLONET TO FILL. APPARENT, OVER-FILLING OF THE CENTER BALLONET RESULTED IN CRUSHING OF THE COLLAPSIBLE TUBE (TRUNKING) THAT WAS USED TO FILL THE FORE & AFT BALLONETS. THERE WAS EVIDENCE THAT AS THE AIRSHIP DESCENDED, THE TRUNKING REMAINED CRUSHED, THE ENVELOPE PRESSURE DROPPED, & THE FORE & AFT BALLONETS WOULD NOT CONTROL THE TRIM OF THE AIRSHIP. A POSTACCIDENT CHECK OF THE CENTER DAMPER VALVE REVEALED THAT IT WAS OPERABLE; THIS VALVE WAS FOR MAINTENANCE USE ONLY & SHOULD HAVE BEEN CLOSED FOR FLIGHT. THE CREW REPORTED HELIUM CONTAMINATION DURING SEVERAL DAYS PRECEDING THE ACCIDENT. PURIFICATION OF THE HELIUM HAD NOT BEEN ATTAINED & MORE HAD BEEN ADDED TO KEEP THE TOTAL AMOUNT HIGH, WHICH RESULTED IN LESS SPACE FOR THE FORE & AFT BALLONETS TO EXPAND.
NTSB Probable Cause Narrative
INADEQUATE DESIGN OF THE AIRSHIP, WHICH ALLOWED THE CENTER BALLONET TO OVERFILL AND TO COLLAPSE THE TRUNKING TO THE FORE AND AFT BALLONETS, RENDERING THE AIRSHIP UNCONTROLLABLE. FACTORS RELATED TO THE ACCIDENT WERE: INADEQUATE MAINTENANCE BY THE COMPANY/OPERATOR, WHICH ALLOWED THE PURITY OF THE HELIUM TO DECREASE; AND THE CENTER DAMPER VALVE TO OPEN (OR TO BE LEFT OPEN FOR FLIGHT).
Event Information
| Type of Event | Accident |
| Event Date | 9/11/1994 |
| Event Day of the Week | Sunday |
| Time of Event | 1111 |
| Event Time Zone | Eastern Daylight Time |
| Event City | FARMINGDALE |
| Event State | NEW YORK |
| Event Country | -- |
| Zipcode of the event site | 11735 |
| Event Date Year | 1994 |
| Event Date Month | 9 |
| MidAir Collision Indicator | No |
| On Ground Collision occurred ? | No |
| Event Location Latitude | |
| Event Location Longitude | |
| 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 | 1 |
| Degrees magnetic from airport | 90 |
| Airport Elevation | -- |
| Weather Briefing Completeness | Not pertinent |
| Investigator's weather source | Pilot |
| Time of the weather observation | 0 |
| Direction of event from weather observation facility (degrees) | 0 |
| Weather Observation Facility ID | |
| Elevation of weather observation facility | 0 |
| Distance of event from weather observation facility (units?) | 0 |
| Time Zone of the weather observation | |
| Lighting Conditions | Day |
| Lowest Ceiling Height | 0 |
| Lowest Non-Ceiling Height | 0 |
| Sky/Lowest/Cloud Conditions | Clear |
| Sky Condition for Lowest Ceiling | None |
| Visibility Runway Visual Range (Feet) | 0 |
| Visibility Runway Visual Value (Statute Miles) | 0 |
| Visibility (Statute Miles) | 30 |
| Air Temperature at event time (in degrees celsius) | 16 |
| Dew Point at event time (in degress fahrenheit) | -- |
| Wind Direction (degrees magnetic) | 300 |
| Variable Wind Indicator | Unknown |
| Wind Speed (knots) | 12 |
| Wind Velocity Indicator | Unknown |
| Wind Gust Indicator | Not Gusting |
| Wind Gust (knots) | 0 |
| Altimeter Setting at event time (in. Hg) | -- |
| Density Altitude (feet) | -- |
| Intensity of Precipitation | Unknown |
| METAR weather report | -- |
| Event Highest Injury | None |
| On Ground, Fatal Injuries | 0 |
| On Ground, Minor Injuries | 0 |
| On Ground, Serious Injuries | 0 |
| Injury Total Fatal | -- |
| Injury Total Minor | -- |
| Injury Total None | 3 |
| Injury Total Serious | -- |
| Injury Total All | -- |
| Investigating Agency | NTSB |
| NTSB Docket Number (internal use) | 1849 |
| NTSB Notification Source | -- |
| NTSB Notification Date | Sep 11 1994 12:00AM |
| NTSB Notification Time | 1145 |
| Fiche Number and/or location -used to find docket information | IMAGE |
| Date of most recent change to record | Dec 6 2000 12:17PM |
| User who most recently changed record | dbo |
| Basic weather conditions | Visual Meteorological Cond |
| FAA District Office | -- |
Aircraft Involved |
|
|---|---|
Aircraft #1 |
|
| Aircraft Registration Number | N317TW |
| NTSB Number | NYC94FA176 |
| Missing Aircraft Indicator | N |
| Federal Aviation Reg. Part | Part 91: General Aviation |
| Type of Flight Plan filed | None |
| Flight plan Was Activated? | -- |
| Damage | Substantial |
| Aircraft Fire | None |
| Aircraft Explosion | None |
| Aircraft Manufacturer's Full Name | WDL |
| Aircraft Model | 1B |
| Aircraft Series Identifier | 1B |
| Aircraft Serial Number | 105 |
| Certified Max Gross Weight | 7000 |
| Aircraft Category | Blimp |
| 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 | Fixed |
| Aircraft, Type of Last Inspection | AAIP |
| Date of Last Inspection | Sep 6 1994 12:00AM |
| Airframe hours since last inspection | 23 |
| Airframe Hours | 3965 |
| ELT Installed | No |
| ELT Activated | Unknown |
| ELT Aided Location of Event Site | Unknown |
| ELT Type | -- |
| Aircraft Owner Name | WDL AIRSHIP INC. |
| Aircraft Owner Street Address | 1013 CENTRE RD. |
| Aircraft Owner City | WILMINGTON |
| Aircraft Owner State | DE |
| Aircraft Owner Country | |
| Aircraft Owner Zipcode | 19805 |
| Operator is an individual? | -- |
| Operator Name | AIRSHIP INERNATIONAL |
| Operator Same as Owner? | No |
| Operator Is Doing Business As | -- |
| Operator Address Same as Owner? | No |
| Operator Street Address | 7380 SAND LAKE RD. |
| Operator City | ORLANDO |
| Operator State | FL |
| Operator Country | |
| Operator Zip code | 32819 |
| Operator Code | |
| Owner has at least one certificate | None |
| Other Operator of large aircraft? | No |
| Certified for Part 133 or 137 Operation | Unknown |
| 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) | Aerial Observation |
| Second Pilot on Board | Yes |
| Departure Point Same as Event | No |
| Departure Airport Code | FRG |
| Departure City | FARMINGDALE |
| Departure State | NY |
| Departure Country | |
| Departure Time | 1020 |
| Departure Time Zone | EDT |
| 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 | Approach |
| Report sent to ICAO? | -- |
| Evacuation occurred | -- |
| Date of most recent change to record | Jan 2 2001 10:30AM |
| User who most recently changed record | dbo |
| Since inspection or accident | -- |
| Event Location Runway Number and Location | 0 |
| Runway Length | -- |
| Runway Width | -- |
| Sight Seeing flight | No |
| Air Medical Flight | No |
| Medical Flight | -- |