# NTSB MIA97LA222: Waco YMF5, N14128, Lake Buena Vist, FL, July 28, 1997 - Type: NTSB accident investigation - Classification: Accident · No injuries · Limited investigation · Final report - Date: July 28, 1997, 16:40 local (20:40 UTC) - Place: Lake Buena Vist, FL - Coordinates: 28.370544, -81.550949 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=28.3705&lon=-81.5509&mi=10 - Phase of flight: [Enroute](https://openairdocs.org/ntsb-phases/400) (OpenAirDocs' grouping) - Highest injury: No injuries - Injuries: 3 uninjured - Status: Completed, report May 29, 1998 - Report: Approved by Office Director - NTSB case key (mKey): 38318 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=MIA97LA222 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/38318/pdf - Page: https://openairdocs.org/ntsb/MIA97LA222 ## Probable cause failure of maintenance personnel to follow installation procedures pertaining to the torque of the propeller retention nut, which resulted in a loose propeller retention nut, subsequent fatigue failure of the crankshaft, and loss of engine power. The lack of suitable terrain for an emergency landing was a related factor. ## Sequence of events In NTSB's coding before 2008 (https://www.ntsb.gov/GILS/Documents/codman.pdf). - Loss of engine power(total) - mech failure/malf, cruise - propeller system/accessories,prop blade retention - loose part/bolt/nut/clamp/etc (cause) - maintenance,installation - improper, company maintenance personnel (cause) - miscellaneous,engine - vibration - engine assembly,crankshaft - fatigue (cause) - engine assembly,crankshaft - failure,total (cause) - Forced landing, emergency descent/landing - On ground/water collision with object, emergency landing - terrain condition - none suitable (contributing factor) - terrain condition - ditch (contributing factor) - ground loop/swerve - intentional, pilot in command - object - pole ## Analysis During cruise flight, the pilot noted an engine vibration followed by a total loss of engine power. He made a forced landing, but was unable to reach suitable terrain. During the landing rollout, he observed a ditch and intentionally ground looped the airplane, but the airplane collided with a pole. Examination of the propeller revealed the propeller retention nut was hand tight. Galling was present on the propeller hub mounting flange and the rear cone. Disassembly of the engine assembly revealed the crankshaft was broken at the counterweight flange. Visual inspection of the shear surfaces on the crankcase showed tell tale benchmarks that appeared to have originated at the oil way plug threads and progressed through approximately one fifth of the crank circumference. Interviews with personnel involved with the installation revealed they had retorqued the propeller, but had not followed accepted industry practices in establishing proper hub to rear cone contact surfaces. ## Factual narrative On July 28, 1997, about 1640 eastern daylight time, a Waco YMF5, N14128, registered to Waco Flying LTD, operated by Reilly Aviation, as a 14 CFR Part 91 sightseeing flight, experienced an engine vibration, followed by a total loss of engine power while in cruise flight. The pilot made a forced landing in the vicinity of Lake Buena Vista, Florida, and collided with a fixed object. Visual meteorological conditions prevailed and no flight plan was filed. The airplane sustained substantial damage. The airline transport pilot and two passengers reported no injuries. The flight originated from Kissimmee, Florida, about 30 minutes before the accident. The pilot stated he was at 1,000 feet when the engine started to vibrate. He made a turn in the direction of a known short takeoff and landing airport (stol), and the engine quit. He maneuvered the airplane to the only available forced landing area (grassy area about 500 feet in length). On touchdown he observed a crossroad with a ditch. He intentionally ground looped the airplane to avoid a collision with the ditch, and the left horizontal stabilizer collided with a mono rail pillar. According to the FAA, examination of the propeller assembly revealed the propeller retention nut was hand tight. Galling was present on the propeller hub mounting flange and rear cone. Disassembly of the Jacobs engine assembly revealed the crankshaft was broken at the counterweight flange. "Visual inspection of the shear surfaces on the crankcase showed tell tale benchmarks that appeared to have originated at the oil way plug threads and progressed through approximately one fifth of the crank circumference. The remainder of the shear surface exhibited a rough irregular surface with a dull gray coloration commonly associated with instantaneous shearing failures." The failed portion of the crankshaft was forwarded to the NTSB Materials Laboratory for examination. Review of aircraft records revealed that Radial Engines, LTD, FAA Certificated Repair Station (CRS) No. RAQR194K overhauled and approved the engine for return to service on April 8, 1997, on work order 10208. The work order indicates that the internal engine components were magnafluxed by D & B Aircraft Engines, FAA CRS No. HX2R888K, and that a maintenance release for the non destructive inspection was issued on October 25, 1990. "Surveillance of Radial Engines, LTD, has established that they are not equipped to perform Magnetic Particle Inspection. D & B aircraft engines is rated to perform maintenance on opposed aircraft engines manufactured by Lycoming, Continental, and Franklin only. D & B aircraft engines is not rated to perform Non Destructive Inspection, by the FAA." Examination of the crankshaft by the NTSB Materials Laboratory revealed separation of the crankshaft was the result of fatigue cracking that initiated in the radius between the bearing surface and the forward face of the forward crankcheek. The fatigue cracking progressed through slightly less than half of the transverse cross section of the shaft portion of the crankshaft, turned and propagated through a portion of the one side of the crankcase before final separation. For additional information see, NTSB Metallurgist's Factual Report No. 98-30. Interviews with personnel involved with the installation of the engine revealed they had retorqued the propeller, but they had not followed accepted industry practices in establishing proper hub to rear cone contact surfaces. A minimum of 70% contact for these surfaces is a required industry standard. Discussions with industry personnel familiar with the overhaul and failure modes of small radial engines of this type, and Aircraft Propellers and Controls Training Manual Order No. EA-APC, established that there are basically three failure modes for crankshaft breakage at the crankpin, other than high cycle fatigue or material discontinuity. They are as follows: * Improper indexing of the propeller to the crankshaft * A loosely installed propeller * An out of balance or out of track propeller The crankshaft was released to Mr. Edward T. Reilly, President, Tom Reilly Vintage Aircraft on February 6, 1998. ## Aircraft - Registration: [N14128](https://openairdocs.org/aircraft/N14128), registered now, S/N 4213, built 1934 (OpenAirDocs) - Reported make and model: Waco YMF5 - Registry model: [Waco YMF](https://openairdocs.org/model/waco-ymf) (registry code 9600411) (OpenAirDocs) - Registry engine: [Jacobs L4 /R755-7](https://openairdocs.org/engine/jacobs-l4-r755-7) (registry code 35003, reciprocating) (OpenAirDocs) - Category: Airplane - Serial number: 4213 - Airframe hours: 4045 - Engines: Jacobs R-755-9 245 horsepower reciprocating - Damage: Substantial damage - Flight: Part 91 - Operator: Reilly Aviation - Registered owner: Waco Flying Ltd - Airworthiness certificate: Standard, Normal - Last inspection: Continuous airworthiness, July 6, 1997, 33 hours before - Departed: ISM, KISSIMMEE, FL ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 66; airline transport; airplane ratings: multi-engine land, single-engine sea, single-engine land; instrument ratings: airplane, helicopter; medical: class 2, valid medical--w/ waivers/lim; seat: right; flight hours: 6,636 total, 179 in this make and model, 5,973 as pilot in command, 225 in the last 90 days, 72 in the last 30 days, 2 in the last 24 hours ## Weather - Conditions: Visual (VMC), Day - Wind: 200° at 5 knots - Visibility: 10 statute miles - Lowest ceiling: 5,000 ft broken - Temperature: 91 °F, dew point 72 °F - Altimeter: 30.00 inHg - Observed at: MCO, 20 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 19970728023559A](https://openairdocs.org/incident/19970728023559A), Jul 28, 1997: Waco YMF, Lake Buena Vist, FL, Substantial damage. Engine quit at cruise. Landed short field had to ground loop. Damaged tail broken crankshaft. Repair not legal. (-23) attachment - 1 page FAA airworthiness… ## Other investigations on N14128 (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 MIA97LA058](https://openairdocs.org/ntsb/MIA97LA058), Jan 1, 1997: Waco WMF-5 (N14128), Kissimmee, FL, substantial damage. Probable cause: the pilot's failure to maintain direction control of the airplane after applying the brakes. A factor was the pilot's lack of familiarity with this make and model airplane. 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.