# NTSB CHI06LA088: Irwin Sonex 2180, N514KP, Rockford, IL, February 27, 2006 - Type: NTSB accident investigation - Classification: Accident · No injuries · Limited investigation · Final report - Date: February 27, 2006, 16:45 local (22:45 UTC) - Place: Rockford, IL - Coordinates: 42.297222, -89.138053 - Nearby events: https://openairdocs.org/map.md?lat=42.2972&lon=-89.1381&mi=10 - Phase of flight: [Enroute](https://openairdocs.org/ntsb-phases/400) (OpenAirDocs' grouping) - Highest injury: No injuries - Injuries: 1 uninjured - Status: Completed, report October 3, 2006 - Report: Approved by Office Director - Parties: Federal Aviation Administration - NTSB case key (mKey): 63281 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=CHI06LA088 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/63281/pdf - Page: https://openairdocs.org/ntsb/CHI06LA088 ## Probable cause The loss of engine power due to the restricted movement of the throttle cable during cruise flight. A factor in the accident was the trees contacted during the forced landing. ## Sequence of events In NTSB's coding before 2008 (https://www.ntsb.gov/GILS/Documents/codman.pdf). - Airframe/component/system failure/malfunction, cruise - throttle/power lever,cable - movement restricted (cause) - Forced landing, emergency descent/landing - In flight collision with object, emergency descent/landing - object - tree(s) (contributing factor) - In flight collision with terrain/water, descent - uncontrolled - terrain condition - ground ## Analysis The experimental amateur-built airplane sustained substantial damage on impact with trees and terrain during a forced landing. The pilot reported the throttle stuck during cruise flight. The pilot attempted to get the sticking throttle to release and the throttle stuck in idle position. The kit manufacturer's examination of the throttle cable and carburetor concluded: "The throttle cable was not supported/attached to anything from the firewall to the cockpit control knob. There was a large amount of flex in the cable when the control knob was pushed when resistance was applied to the Carb End of the cable. The only anchor on the throttle cable was a "through the firewall" clamp. ... The AeroCarb was disassembled. ... Nothing internally was found that would cause it to stick." ## Factual narrative On February 27, 2006, about 1645 central standard time (cst), an experimental amateur-built Irwin Sonex 2180 airplane, N514KP, piloted by a private pilot, sustained substantial damage on impact with trees and terrain during a forced landing near Rockford, Illinois. The personal flight was operating under 14 Code of Federal Regulations Part 91. No flight plan was on file. The pilot reported that he sustained no injuries. The flight originated from the Poplar Grove Airport (C77), near Poplar Grove, Illinois, at 1615. The pilot's accident report, in part, stated: Aircraft departed C77 on a personal, recreational flight at approximately 415 pm cst. Pilot performed several throttle sticking tests in the immediate vicinity of C77 and all was o.k. Pilot cruised north of Rockford, IL at approximately 2200 [feet above mean sea level] at 2800 rpm. Just north of Cottonwood Airport (IC8) pilot attempted to increase throttle. It stuck. Pilot attempted to get sticking to release [and] throttle stuck in idle position. Pilot turned toward Cottonwood but when he determined it was out of range, he picked the best available corn field. Upon approach, he pulled up over electrical wires [and] a wind gust pushed the plane into the top of a tree about 25 [feet] up. After impacting the tree, the plane stopped forward movement and fell tail first to the ground. ... The craft then tipped onto its top. Pilot exited through broken canopy. A Federal Aviation Administration Inspector and a representative from the kit manufacturer examined the wreckage to include the throttle cable and carburetor. The kit manufacturer stated: When disconnected from the carb, the Throttle Cable was found to be quite stiff compared to others Sonex Aircraft, LLC has experience with. Note that the owner stated it was smoother prior to the incident. The throttle cable was not supported/attached to anything from the firewall to the cockpit control knob. There was a large amount of flex in the cable when the control knob was pushed when resistance was applied to the Carb End of the cable. The only anchor on the throttle cable was a "through the firewall" clamp. ... The AeroCarb was disassembled. No internal flaws or defects were found other than some very minor scratches. Nothing internally was found that would cause it to stick. ... The Sonex website, www.sonexaircraft.com, was reviewed. The site contains links to service bulletins to include bulletins in reference to sticky throttles. ## Aircraft - Registration: [N514KP](https://openairdocs.org/aircraft/N514KP), registered now, S/N 514, built 2006 (OpenAirDocs) - Reported make and model: Irwin Sonex 2180 - Registry model: [Irwin Kenneth SONEX 2180](https://openairdocs.org/model/irwin-kenneth-sonex-2180) (registry code 056190V) (OpenAirDocs) - Registry engine: [Amateur-built UNKNOWN ENG](https://openairdocs.org/engine/amateur-built-unknown-eng) (registry code 99999) (OpenAirDocs) - Category: Airplane, amateur-built - Serial number: 514 - Airframe hours: 18.5 - Engines: Aero Vee 2180 80 horsepower reciprocating - Damage: Substantial damage - Flight: Personal, Part 91 - Registered owner: Ken Irwin - Airworthiness certificate: Special, Experimental (Special) - Last inspection: Condition, February 1, 2006 - Departed: C77, POPLAR GROVE, IL ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 53; injuries: minor; private; airplane ratings: single-engine land; instrument ratings: airplane; medical: class 3, with waivers/limitations; last flight review July 1, 2005; seat: left; flight hours: 742 total, 18 in this make and model, 667 as pilot in command, 18 in the last 90 days, 13 in the last 30 days, 1 in the last 24 hours ## Weather - Conditions: Visual (VMC), Day - Wind: 60° at 15 knots - Visibility: 10 statute miles - Lowest ceiling: none - Temperature: 36 °F, dew point 21 °F - Altimeter: 29.98 inHg - Observed at: RFD, 6 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 20060227006149A](https://openairdocs.org/incident/20060227006149A), Feb 27, 2006: Amtr SONEX, Rockford, IL, Substantial damage. (-23) Aircraft was at cruise, while pilot was trying to adjust throttle control. Pilot reported that throttle cable was slightly hard to move, so while trying… 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.