# NTSB CHI93DEE05: Weatherly 620, N4605P, Mendota, IL, August 14, 1993 - Type: NTSB accident investigation - Classification: Accident · Serious injuries · Final report - Date: August 14, 1993, 16:50 local (21:50 UTC) - Place: Mendota, IL - Coordinates: 41.550041, -89.120384 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=41.5500&lon=-89.1204&mi=10 - Phase of flight: [Maneuvering](https://openairdocs.org/ntsb-phases/450) (OpenAirDocs' grouping) - Highest injury: Serious injuries - Injuries: 1 serious - Status: Completed, report August 17, 1994 - Report: Approved by Office Director - NTSB case key (mKey): 9140 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=CHI93DEE05 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/9140/pdf - Page: https://openairdocs.org/ntsb/CHI93DEE05 ## Probable cause THE PILOT-IN-COMMAND'S FAILURE TO MAINTAIN CLEARANCE FOM POWERLINES DURING AN AERIAL APPLICATION MANUEVER. ## Sequence of events In NTSB's coding before 2008 (https://www.ntsb.gov/GILS/Documents/codman.pdf). - In flight collision with object, maneuvering - aerial application - object - wire,transmission - clearance - not maintained, pilot in command (cause) - In flight collision with terrain/water, descent - uncontrolled ## Analysis THE PILOT HAD MADE TWO PASSES MANEUVERING UNDER POWERLINES ON AN AERIAL APPLICATION APPLYING CHEMICALS TO A FIELD. AS THE PILOT BEGAN MAKING HIS THIRD PASS, THE AIRPLANE STRUCK THE POWERLINES. THE AIRPLANE IMPACTED THE GROUND, SKIDDED, AND CAME TO REST APPROXIMATELY 120 YARDS FROM THE POWERLINES. ## Factual narrative HISTORY OF FLIGHT On August 14, 1993, at 1650 CDT, a Weatherly Model 620 owned by Hendrickson Flying Service of Rochelle, Illinois, struck electrical transmission lines during an aerial application operation and fell to the ground near Mendota, Illinois. VFR flight conditions prevailed and no flight plan was filed. The aircraft was destroyed and the pilot received serious injuries. The flight originated at Grandpa's Farm (0C7), Mendota, Illinois, about 1630 CDT. OTHER DAMAGE Approximately one acre of corn was damaged by the aircraft as it skidded to a stop. CREW INFORMATION The pilot, Robert F. Hess, age 44, holds commercial pilot certificate No. 480627809 issued on January 31, 1989, with airplane ratings for single and multiengine land aircraft. The most recent second class medical certificate was issued to the pilot on February 2, 1993, and contained the limitation that correcting lenses be worn while exercising the privileges of his airman's certificate. AIRCRAFT INFORMATION Fueling records at Hendrickson Flying Service established that the aircraft was last fueled on August 14, 1993, with the addition of approximately 25 gallons of 100 octane aviation fuel. The maintenance records revealed no unresolved maintenance discrepancies against the aircraft prior to departure. WRECKAGE AND IMPACT INFORMATION The accident site is a triangular shaped level farm field of approximately 58 acres bordered by electrical transmission lines on the east and south sides. The pilot had made two passes from east to west, flying under the power lines, applying chemicals. As the pilot began making his third pass, the aircraft's propeller and vertical stabilizer struck the 34,000 volt transmission line on the east side of the field. The transmission line remained intact, however some of the insulation was torn off. The aircraft's vertical stabilizer separated from the empennage after contacting the transmission line and fell to the ground approximately 15 yards west of the power lines. Measurements taken by the power line repair crew placed the height of the wire at 42 feet above ground level. The lone witness reported the aircraft's nose pitched down after striking the wire. Crop damage and ground scars began approximately 50 yards west of the power lines. Impact marks in the ground indicate the aircraft crashed in a slight nose low attitude at a high vertical sink rate. Both main landing gear broke off the aircraft and the spray booms which were suspended under the trailing edge of the wings separated from their attach points. The propeller and engine struck the ground with sufficient force to break the engine mounts and destroy the chemical hopper which was located between the engine and cockpit. The fuselage came to rest approximately 120 yards west of the power lines on a southerly heading, which was about right angles to the path of flight. Both wings and the fuselage area forward of the cockpit were destroyed by impact forces. The cockpit area aft to the tail section remained relatively intact. SURVIVAL ASPECTS The cockpit area of the aircraft remained intact. The seat supports and restraint system suffered damage from the crash impact. The steel tubular seat supports showed some forward distortion and one support was broken at a weld joint. The shoulder harness attach point failed in a forward direction, allowing the pilot to be thrown against the aircraft instrument panel. The aircraft instrument panel was caved in with approximately the same radius that the shoulder harness attach point was bowed forward. Rescue personnel found it necessary to cut one seat support to facilitate removal of the pilot from the wreckage. ## Aircraft - Registration: [N4605P](https://openairdocs.org/deregistered/N4605P-1994-07-13), registration cancelled 1994-07-13, S/N 1507 (OpenAirDocs) - Reported make and model: WEATHERLY 620 - Registry model: [Weatherly 620](https://openairdocs.org/model/weatherly-620) (registry code 9630602) (OpenAirDocs) - Category: Airplane - Serial number: 1507 - Airframe hours: 3906 - Engines: P&W R-985-ANI 450 horsepower reciprocating - Damage: Destroyed - Flight: Aerial application, Part 137 - Operator: Hendrickson Flying Service - Registered owner: Hendrickson Flying Service - Airworthiness certificate: Special, Restricted (Special) - Last inspection: Annual, June 5, 1993, 290 hours before ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 44; commercial; airplane ratings: multi-engine land, single-engine land; instrument ratings: airplane; medical: class 2, valid medical--w/ waivers/lim; seat: center; flight hours: 3,745 total, 1,220 in this make and model, 3,566 as pilot in command ## Weather - Conditions: Visual (VMC), Day - Wind: 160° at 4 knots - Visibility: 10 statute miles - Lowest ceiling: none - Temperature: 84 °F, dew point 72 °F - Altimeter: 30.00 inHg - Observed at: SQI, 29 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 19930814029259A](https://openairdocs.org/incident/19930814029259A), Aug 14, 1993: Wthrly 620, Mendota, IL, Destroyed. Struck powerline during spray run under wires. Impact tore off vertical stabilizer. Aircraft crashed beyond line. ## Other investigations on N4605P (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 CHI88DEE05](https://openairdocs.org/ntsb/CHI88DEE05), Jul 11, 1988: Weatherly 620 (N4605P), Dekalb, IL, substantial damage. Probable cause: AN ON GROUND ENCOUNTER WITH WEATHER. 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.