# NTSB MIA99LA117: Waco YMF-5, N820MM, Boca Raton, FL, April 2, 1999 - Type: NTSB accident investigation - Classification: Accident · Serious injuries · Limited investigation · Final report - Date: April 2, 1999, 15:57 local (20:57 UTC) - Place: Boca Raton, FL - Location: 26.3708° N, 80.1026° W: Placed by OpenAirDocs: center of Boca Raton, FL, within about 6 miles (OpenAirDocs) - Nearby events: https://openairdocs.org/map.md?lat=26.3708&lon=-80.1026&mi=10 - Phase of flight: [Maneuvering](https://openairdocs.org/ntsb-phases/450) (OpenAirDocs' grouping) - Highest injury: Serious injuries - Injuries: 1 serious, 1 minor - Status: Completed, report April 19, 2001 - Report: Approved by Office Director - NTSB case key (mKey): 46033 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=MIA99LA117 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/46033/pdf - Page: https://openairdocs.org/ntsb/MIA99LA117 ## Probable cause The pilot's failure to select a suitable forced landing site following a partial loss of engine power due to failed cylinder holdddown studs, and the subsequent collision with trees. A factor in the accident was the reduced forward visibility from the dual open cockpits due to windshield obscuration by engine oil. ## Sequence of events In NTSB's coding before 2008 (https://www.ntsb.gov/GILS/Documents/codman.pdf). - Loss of engine power(partial) - mech failure/malf, maneuvering - engine assembly,other - fractured - reason for occurrence undetermined - Forced landing, emergency descent/landing - visual lookout - restricted, pilot in command (contributing factor) - unsuitable terrain or takeoff/landing/taxi area - selected, pilot in command (cause) - In flight collision with object, emergency landing - object - tree(s) ## Analysis The pilot reported that during maneuvering flight, at about 500 feet agl, and 1/2 mile offshore, the engine and cowling began to shake, the engine began to sputter, and the windscreens became covered with oil. He made a turn westbound toward land, and declared an emergency, intending to land at the nearest airport. He reported the engine power available would not sustain level flight, and he started a slow descent. Neither the pilot nor his front seat passenger acquired a visual on the airport. The pilot overflew the airport and forced landed in a residential area 2 miles west of the airport. Examination of the engine revealed failure of the 12 cylinder holddown studs of the No. 7 cylinder. ## Factual narrative On April 2,1999, about 1557 eastern standard time, a Waco YMF-5, N820MM, registered to MD Aero, Inc., operating as a 14 CFR Part 91 personal flight, crashed in a residential area in Boca Raton, Florida, following an engine failure. Visual meteorological conditions prevailed and no flight plan was filed. The airplane received substantial damage, the private-rated pilot sustained serious injuries, and a passenger sustained minor injuries. The flight originated from Fort Lauderdale's Executive Airport (FXE), about 17 minutes before the accident. According to the pilot, the flight was maneuvering at 500 feet agl, about 1/2 mile off the coast northeast of Boca Raton when the engine and cowling began to shake, the engine began to sputter, and the windscreens became covered with oil. He stated that the engine power available was not enough to sustain level flight, so he set up a slow rate of descent and an immediate turn westbound. He declared an emergency with FAA Pompano Control Tower, told them he would try to make an emergency landing at Boca Raton Airport, and was given the unicom frequency for Boca Raton. He switched to the Boca frequency and raised a young woman's voice who said she would get help. He stated he could hear other aircraft in the traffic pattern stating they would yield to the emergency, but he made no further calls. At about 1543, according to FAA Pompano Control Tower personnel, N820MM called that he just departed FXE eastbound and asked for clearance to transit their area along the beach in a south to north direction. At about 1552, he had reached the northern limit of Pompano's airspace and was cleared for a radio frequency change. At about 1554, Pompano tower heard a Mayday call from N820MM, and at about 1555, the pilot said he had an oil leak and would try to land at the Boca Raton Airport. According to a pilot in the traffic pattern at Boca Raton Airport, when N820MM declared his emergency and stated his engine problem, he obtained a visual on the Waco and watched him proceed westbound from a point about 2 miles east of the airport. It became obvious to the pilot that the Waco pilot and passenger did not or could not see the Boca airport, because they flew "..right over the numbers for runway 23 at Boca, but kept on flying westbound". According to the Boca Raton Police Services Department, the pilot advised them that the airplane "..developed engine problems and was trying to make Boca Raton Airport and was unable to see the runway and overshot the airport and crashed in the field." The airplane collided with trees in a residential area and came to rest inverted. According to FAA inspectors, the airplane crashed about 2 miles west of the Boca Raton Airport, within a residential area. Postcrash examination of the Jacobs radial engine by FAA inspectors revealed the power loss was caused by the failure of the No. 7 cylinder holddown studs and the resultant lifting of the cylinder off its seat. Three of a total of 12 holddown studs, located on the aft side of the cylinder, revealed rust on their fractured surfaces. The remaining studs exhibited overload fractures. Piston wear marks on the walls of No. 7 cylinder reveal tilting of the cylinder away from the studs with rusted fracture sites. The power loss and oil leakage were the result of induction piping and oil line connections being stripped when the cylinder started lifting off its seat. Inspectors reported that the only thing holding No. 7 cylinder on the engine was baffling jammed against the cowl. About 140 engine operating hours before the accident, on March 3, 1998, the engine was reinstalled by General Aviation, Inc. of Lansing, Michigan, after a Jacobs Engine, Inc. factory teardown inspection due to a landing nose over incident. ## Aircraft - Registration: [N820MM](https://openairdocs.org/deregistered/N820MM-2007-10-26), registration cancelled 2007-10-26, S/N F5C-056, built 1993 (OpenAirDocs) - Reported make and model: Waco YMF-5 - Registry model: [Classic WACO YMF](https://openairdocs.org/model/classic-waco-ymf) (registry code 2240101) (OpenAirDocs) - Registry engine: [Jacobs R755B series](https://openairdocs.org/engine/jacobs-r755b-series) (registry code 35007, reciprocating) (OpenAirDocs) - Category: Airplane - Serial number: F5C056 - Airframe hours: 731 - Engines: Jacobs R755B2M 275 horsepower reciprocating - Damage: Substantial damage - Flight: Personal, Part 91 - Registered owner: Md Aero, Inc. - Airworthiness certificate: Standard, Normal - Last inspection: Annual, April 3, 1998, 156 hours before - Departed: FXE, FT. LAUDERDALE, FL ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 64; private; airplane ratings: single-engine land; instrument ratings: airplane; medical: class 3, valid medical--w/ waivers/lim; seat: rear; flight hours: 2,228 total, 547 in this make and model, 2,088 as pilot in command, 36 in the last 90 days, 15 in the last 30 days, 3 in the last 24 hours ## Weather - Conditions: Visual (VMC), Day - Wind: 130° at 10 knots - Visibility: 10 statute miles - Lowest ceiling: 6,000 ft broken - Temperature: 82 °F, dew point 72 °F - Altimeter: 30.00 inHg - Observed at: PBI, 21 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 19990402003039A](https://openairdocs.org/incident/19990402003039A), Apr 2, 1999: Waco YMF, Baco Raton, FL, Substantial damage. Pilot reported that oil was leaking onto the acft wiandshield and that he was trying to make it to the arpt, the acft overflew the arpt due to oil on he… ## Other investigations on N820MM (1) 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. - [NTSB CHI97LA170](https://openairdocs.org/ntsb/CHI97LA170), Jun 14, 1997: Waco YMF (N820MM), Longville, MN, substantial damage. Probable cause: failure of the pilot to maintain directional control of the airplane. Factors relating to the accident were: the gusty wind condition and the ditch. 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.