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| Date: | Thursday 28 July 1983 |
| Time: | 12:03 |
| Type: |  Fairchild Hiller FH-1100 |
| Owner/operator: | Hiller Aviation |
| Registration: | N450FH |
| MSN: | 215 |
| Total airframe hrs: | 5288 hours |
| Engine model: | ALLISON 250-C18 |
| Fatalities: | Fatalities: 2 / Occupants: 2 |
| Other fatalities: | 0 |
| Aircraft damage: | Destroyed |
| Category: | Accident |
| Location: | Porterville, CA -
 United States of America
|
| Phase: | Manoeuvring (airshow, firefighting, ag.ops.) |
| Nature: | Unknown |
| Departure airport: | |
| Investigating agency: | NTSB |
| Confidence Rating: |  Accident investigation report completed and information captured |
ON 7/27/83, MILD MAST BUMPING OCCURRED DURING A PUSHOVER MANEUVER WHILE A HILLER FH-1100 WAS ON A FLT TO CERTIFY NEW ROTOR BLADES. PRIOR TO THE INCIDENT, THE HELICOPTER WAS ACCELERATED TO 90 MPH. THIS WAS FOLLOWED BY A PULL-UP & DECELERATION TO 80 MPH, THEN THE PUSHOVER WAS INITIATED. THE HELICOPTER REPORTEDLY ROLLED SHARPLY TO THE RIGHT & PITCHEDNOSE DOWN WITH SOME YAW TO THE RIGHT. RECOVERY WAS MADE WITH LEFT CYCLIC; HOWEVER, DIRECTIONAL CONTROL WAS LOST BEFORE RECOVERY & MILD MAST BUMPING. ON 7/28/83, FH-1100, N450FH, A STANDARD PRODUCTION MODEL, WAS FLOWN TO EXPLORE THE PHENOMENON. AFTER 2 PUSHOVERS WITH INCREASING SEVERITY, IN WHICH CONTROL WAS RETAINED, THE PLT ATTEMPTED A REPETITION OF THE PREVIOUS DAY'S MANEUVER. WITNESSES OBSERVERVED THE HELICOPTER ROLL & YAW TO THE RIGHT & PITCH DOWN AS IT BEGAN TO BREAK UP, THEN BURN & CRASH. AN EXAM REVEALED THE MAIN ROTOR BLADES SEPARATED AFTER MAST BUMPING & MAST FAILURE OCCURRED. THERE WAS EVIDENCE THE PLT MIGHT NOT HAVE BEEN CURRENT IN TEETERING ROTOR SYSTEMS & RECOVERY FROM LOW G ROLLS. CAUSE:
Accident investigation:
 |
|
Sources:
NTSB: http://www.ntsb.gov/ntsb/brief.asp?ev_id=20001214X43780
Revision history:
| Date/time | Contributor | Updates |
|---|---|---|
| 24-Oct-2008 10:30 | ASN archive | Added |
| 21-Dec-2016 19:23 | ASN Update Bot | Updated [Time, Damage, Category, Investigating agency, ] |
| 15-Jul-2018 12:59 | Greg B | Updated [Narrative, ] |
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