# NTSB MIA99LA119: David C. Bock Challenger II, N929DB, Astatula, FL, April 7, 1999 - Type: NTSB accident investigation - Classification: Accident · No injuries · Limited investigation · Final report - Date: April 7, 1999, 12:15 local (16:15 UTC) - Place: Astatula, FL - Coordinates: 28.710111, -81.730438 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=28.7101&lon=-81.7304&mi=10 - Phase of flight: [Maneuvering](https://openairdocs.org/ntsb-phases/450) (OpenAirDocs' grouping) - Highest injury: No injuries - Injuries: 1 uninjured - Status: Completed, report March 31, 2000 - Report: Approved by Office Director - NTSB case key (mKey): 46069 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=MIA99LA119 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/46069/pdf - Page: https://openairdocs.org/ntsb/MIA99LA119 ## Probable cause The aircraft structure fluttering inflight resulting in fracture of fuselage longerons and the pilot being unable to maintain control. ## Sequence of events In NTSB's coding before 2008 (https://www.ntsb.gov/GILS/Documents/codman.pdf). - Loss of control - in flight, maneuvering - airframe - flutter (cause) - fuselage,longeron - fractured - aircraft control - not possible, pilot in command ## Analysis The pilot was performing Phase I flight testing of the homebuilt aircraft and investigating the upper flight envelope. While descending through 4,000 feet msl at a speed of 115-118 mph, the aircraft began to flutter. He reduced engine power and raised the nose at which time he heard a loud 'pop' noise. The aircraft went out of control, rolling to an inverted position. The pilot activated the aircraft's ballistic recovery parachute and the aircraft and pilot landed in an orange grove. Postcrash examination showed 2 fuselage longerons had fractured. The manufacturer had determined the never exceed speed (Vne) for the aircraft to be 120 mph. ## Factual narrative On April 7, 1999, about 1215 eastern daylight time, a David C. Bock Challenger II, N929DB, registered to an individual, began to flutter and went out of control near Astatula, Florida, while on a Title 14 CFR Part 91 personal flight. Visual meteorological conditions prevailed at the time and no flight plan was filed. The aircraft received substantial damage and the private-rated pilot was not injured. The flight originated from Zellwood, Florida, the same day, about 1130. The pilot stated he was performing Phase I flight testing of the homebuilt aircraft. While investigating the upper flight envelope, he was descending through 4,000 feet, at approximately 115-118 mph. The aircraft began to flutter and vibrate, and the control stick became hard to hold. He reduced engine power and raised the aircraft's nose. He heard a loud "pop" and the aircraft rolled to an inverted position. The aircraft was uncontrollable and he deployed the aircraft's ballistic recovery parachute (BRS). The parachute deployed properly and he and the aircraft floated to the ground, landing in an orange grove, between two trees. The kit manufacturer estimated the never exceed speed (Vne) to be 120 mph. In earlier tests the aircraft was fully controllable to 110 mph. Postcrash examination of the aircraft showed that one of two main, 2-inch diameter longerons in the tail had fractured as well as a 1-inch diameter longeron. ## Aircraft - Registration: [N929DB](https://openairdocs.org/deregistered/N929DB-1999-06-18), registration cancelled 1999-06-18, S/N CH20496CW1479 (OpenAirDocs) - Reported make and model: David C. Bock CHALLENGER II (CHALLENGER) - Registry model: [Bock David C CHLNGR II CLP WG SP](https://openairdocs.org/model/bock-david-c-chlngr-ii-clp-wg-sp) (registry code 05606TK) (OpenAirDocs) - Category: Airplane, amateur-built - Serial number: CH20496CW147 - Airframe hours: 9 - Engines: Rotax 503 50 horsepower reciprocating - Damage: Substantial damage - Flight: Personal, Part 91 - Registered owner: David C. Bock - Airworthiness certificate: Special, Experimental (Special) - Last inspection: Annual, April 1, 1999, 9 hours before - Departed: X61, ZELLWOOD, FL ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 36; private; airplane ratings: single-engine land; medical: class 3, valid medical--no waivers/lim.; seat: front; flight hours: 208 total, 13 in this make and model, 208 as pilot in command, 13 in the last 90 days, 13 in the last 30 days, 5 in the last 24 hours ## Weather - Conditions: Visual (VMC), Day - Wind: 90° at 6 knots - Visibility: 10 statute miles - Lowest ceiling: none - Temperature: 84 °F, dew point 59 °F - Altimeter: 30.00 inHg - Observed at: ORL, 15 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 19990407003199A](https://openairdocs.org/incident/19990407003199A), Apr 7, 1999: Semco CHALLENGER, Zellwood, FL, Substantial damage. Acft experienced unknown problems and the pilot bailed out using a parachute, the acft subsequently crashed and sustained substantial damage. The pilot was not… 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.