# NTSB CEN11FA433: Klemp Gregory J Challenger II, N12911, Neshkoro, WI, June 30, 2011 - Type: NTSB accident investigation - Classification: Accident · Fatal · Field investigation · Final report - Date: June 29, 2011, 19:45 local (Jun 30, 2011, 00:45 UTC) - Place: Neshkoro, WI - Coordinates: 44.041389, -89.304443 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=44.0414&lon=-89.3044&mi=10 - Phase of flight: [Initial climb](https://openairdocs.org/ntsb-phases/350) (OpenAirDocs' grouping) - Defining event: [Initial climb: Loss of engine power (total)](https://openairdocs.org/ntsb-events/341) - Highest injury: Fatal - Injuries: 1 fatal, 1 serious - Status: Completed, report April 20, 2012 - Report: Approved by Office Director - NTSB office: Central Region - Parties: Federal Aviation Administration - NTSB case key (mKey): 80949 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=CEN11FA433 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/80949/pdf - NTSB docket: https://data.ntsb.gov/Docket?ProjectID=80949 - Page: https://openairdocs.org/ntsb/CEN11FA433 ## Probable cause The total loss of engine power during the initial climb due to a cold seizure as a result of a broken fan V-belt. Contributing to the accident was the passenger's interference with the flight controls during the forced landing. ## Findings NTSB's coded findings; those marked are part of the probable cause. - [Engine (reciprocating): recip eng cyl section](https://openairdocs.org/ntsb-findings/01058530): Aircraft › Aircraft power plant · Malfunction (probable cause); cases with it: [Klemp Gregory J CHALLENGER II, 1 case](https://openairdocs.org/ntsb-findings/01058530/cases.md?model=056281B), [All aircraft, 373 cases](https://openairdocs.org/ntsb-findings/01058530/cases.md) - [Mental/emotional state: anxiety/panic](https://openairdocs.org/ntsb-findings/02022515): Personnel issues › Psychological · Passenger (probable cause); cases with it: [Klemp Gregory J CHALLENGER II, 1 case](https://openairdocs.org/ntsb-findings/02022515/cases.md?model=056281B), [All aircraft, 10 cases](https://openairdocs.org/ntsb-findings/02022515/cases.md) ## Sequence of events The events NTSB coded, in order, by phase of flight. The defining event best describes what happened. - [Initial climb: Loss of engine power (total)](https://openairdocs.org/ntsb-events/341) (defining event); cases with it: [Klemp Gregory J CHALLENGER II, 1 case](https://openairdocs.org/ntsb-events/341/sequence.md?model=056281B), [All aircraft, 3,820 cases](https://openairdocs.org/ntsb-events/341/sequence.md) - [Emergency descent: Collision with terr/obj (non-CFIT) ](https://openairdocs.org/ntsb-events/470); cases with it: [Klemp Gregory J CHALLENGER II, 1 case](https://openairdocs.org/ntsb-events/470/sequence.md?model=056281B), [All aircraft, 10,189 cases](https://openairdocs.org/ntsb-events/470/sequence.md) ## Analysis Prior to the local flight, the pilot, who was seated in the rear seat, completed a preflight check and engine run-up. During the initial climb, at 1,200 feet above ground level, the engine lost total power and the pilot initiated a forced landing to a private grass airstrip. While maneuvering the airplane for the forced landing, the pilot felt his left rudder pedal pressed to the floor. The pilot thought that the passenger may have been frightened and stepped on the rudder pedal. The pilot instructed to the passenger to release the rudder pedal as the airplane entered into a slip and was losing altitude; however, the passenger did not respond to the pilot. Due to the loss of altitude, the airplane was unable to reach the airstrip and impacted trees. A postaccident examination of the engine revealed that the cooling fan V-belt was broken and that the pistons exhibited scoring signatures consistent with a cold seizure. According to the manufacturer, the engine is susceptible to cold seizures when there is inadequate cooling of the cylinders, such as with a broken cooling fan V-belt. Review of the engine manufacturer’s installation and operations manual revealed warnings that "the engine by design is subject to sudden stoppage," and that it does not conform to aircraft standards. ## Factual narrative HISTORY OF FLIGHT On June 29, 2011, approximately 1945 central daylight time, a Klemp Challenger II experimental amateur-built airplane, N12911, impacted trees and terrain during a forced landing following a loss of engine power near Neshkoro, Wisconsin. The private pilot received serious injuries and the non-pilot rated passenger was fatally injuried. The airplane sustained substantial damage during the forced landing. The airplane was registered to and operated by a private individual. Visual meteorological conditions prevailed, and a flight plan was not filed for the 14 Code of Federal Regulations Part 91 personal flight. The local flight departed a private grass airstrip approximately 1930. According to the pilot, he planned on performing a local flight for the passenger who intended on purchasing and building a Challenger airplane. Prior to takeoff, the pilot, who was seated in the rear seat, completed a pre-flight check and engine run-up, and he noted the cylinder head temperature was approximately 250 degrees Fahrenheit. The pilot observed no anomalies during the pre-flight check, engine run-up or takeoff. During the initial climb at 1,200 feet above ground level (agl) while crossing over the runway, the engine experienced a partial loss of engine power. Seconds later, the engine lost total power, and the pilot initiated a forced landing to the private grass airstrip. The controls to restart the engine were located in the front seat position and could not be accessed by the pilot to attempt an engine restart. While maneuvering the airplane for the forced landing to the airstrip, the pilot felt his left rudder pedal pressed to the floor (The front and aft seat rudder pedals are interconnected). The pilot felt the passenger may have been frightened and "froze on the rudder pedal." The pilot instructed to the passenger to release the rudder pedal as the airplane entered into a slip and was losing altitude; however, the passenger did not respond to the pilot. Due to the loss of altitude, the airplane was no longer going to make it to the airstrip, and the pilot then attempted to land off the airstrip with the jammed left rudder. During the landing, the airplane impacted trees and terrain. The airplane came to rest on its right side in tall grass adjacent to trees. PERSONNEL INFORMATION The pilot held a private pilot certificate with single engine land and sea airplane ratings. The pilot's most recent third class medical certificate was issued on November 26, 2010. The pilot estimated his total flight time was 3,000 hours with 2,000 hours in the accident airplane make and model. AIRCRAFT INFORMATION The experimental amateur-built Klemp Challenger II airplane was a two-seat, high-wing, pusher configuration with a primary structure comprised of fabric-covered aluminum tubing, and fixed landing gear. The airplane was assembled by the owner, who is also a dealer for the Challenger model airplanes. The airplane was powered by a Rotax 503 UL DCDIengine and equipped with a two-blade wooded propeller. The engine was mounted above and aft of the cockpit. The Rotax engine was a 2-stroke, 2-cylinder, in-line engine, which utilized an integrated water pump and fan-cooled cylinder heads and cylinders. Review of the engine's installation and operations manuals revealed information indicating the following: "The engine, by design, is subject to sudden stoppage...This is not a certificated aircraft engine. It has not received any safety or durability testing, and conforms to no aircraft standards. It is for use in experimental, uncertificated aircraft and vehicles only in which an engine failure will not compromise safety...User assumes all risk of use, and acknowledges by his use that he knows this engine is subject to sudden stoppage...You should be aware that any engine may seize or stall at any time." According to the maintenance manual, the cooling fan V-belt tensions should be checked on the first 10 hours of engine operation, and then every 25 hours after, until the engine reaches the time before overhaul (TBO) of 300 hours. The operator's manual states that during the pre-flight check, the operator should verify that the cooling fan turns when the engine is rotated. The V-belt should be replaced if frayed or if it can no longer be tensioned to specification. In addition, the periodical maintenance seasonal checks recommend the V-belt should be replaced new every 5 years or as required by condition. The airplane was issued an experimental amateur-built airworthiness certificate on March 5, 2010. The most recent conditional inspection was completed on March 5, 2011. At the time of the accident, the airframe had accumulated 172 total hours, and the owner estimated the engine had approximately 300 total hours since new. The engine logbook, dating back to 1993, did not indicate whether the V-belt had been changed or replaced. METEOROLOGICAL INFORMATION The pilot reported the following weather conditions at the time of the accident: wind calm, visibility 10 miles, and few clouds. WRECKAGE AND IMPACT INFORMATION An examination of the airplane revealed flight control continuity to all flight control surfaces. The two-blade wooden propeller showed no evidence of damage. Approximately 6 gallons of fuel was noted in the fuel tank and fuel was found in the fuel lines and both carburetors. The airplane was recovered upright onto a flat-bed trailer. The carburetor bowls were removed and fuel was noted in each bowl. The bowls were reinstalled and an engine test run was performed. The engine was test run on the airframe at various power settings for approximately 5 minutes utilizing the cockpit engine controls with no anomalies noted. MEDICAL AND PATHOLOGICAL INFORMATION An autopsy was performed on the passenger by the Fond du Lac County Medical Examiner, Fond du Lac, Wisconsin, on June 30, 2011. The autopsy listed the cause of death as multiple traumatic injuries. The Federal Aviation Administration's(FAA) Civil Aerospace Medical Institute performed toxicology on specimens from the passenger. The report noted that Carvedilol was detected in the urine and blood. No carbon monoxide, cyanide, or ethanol was detected. The pilot was treated for serious non-life threatening injuries and released within hours after the accident. No FAA toxicological tests were completed on the pilot. The pilot and passenger were not wearing helmets during the accident flight, nor were they required to per Federal Aviation Regulations. TEST AND RESEARCH On July 6, 2011, at the pilot's hangar, the engine was further examined by the NTSB investigator-in-charge and the pilot. Examination of the engine showed the cooling fan V-belt was broken. The carburetors and exhaust manifold were removed and scoring was noted on the sides of both pistons, consistent with a cold seizure event. The pilot attributed the loss of engine power due to a cold seizure of the engine when the fan V-belt broke during flight. ADDITIONAL INFORMATION According to the engine manufacturer's representative, all seizures are caused by heat/friction and there is a thermo-imbalance of the piston and cylinder, caused by a lack of warm-up or excessive temperature of the engine. A cold seizure is where the piston expands faster than the bore it is traveling in and contacts the sides of that bore. These are also known as four corner seizures. A cold seizure usually occurs after a full throttle run when the engine is powered back to a cruise throttle setting. If the engine has experienced some previous mini seizures, the stoppage can occur anytime in flight as there is already some aluminum (off the piston) attached to the cylinder wall and galling (unwanted removal of aluminum from the piston to cylinder wall) will be occurring at a variable rate. Contributing factors to the piston seizure are: 1. The imbalance of the carburetors allowing the loading of one piston to be greater than the other. 2. Incorrect carburetor venting that could negatively affect carburetor fuel mixture control. 3. Inadequate cooling of the cylinders. I.E. broken fan belt or poor engine cowling 4. Lack of lubrication (Poor oil quality or not enough oil in premixed fuel) ## Aircraft - Registration: [N12911](https://openairdocs.org/aircraft/N12911), registered now, S/N CH2-1296-1544, built 2009 (OpenAirDocs) - Reported make and model: KLEMP GREGORY J CHALLENGER II - Registry model: [Klemp Gregory J CHALLENGER II](https://openairdocs.org/model/klemp-gregory-j-challenger-ii) (registry code 056281B) (OpenAirDocs) - Registry engine: [Rotax 582DCDI](https://openairdocs.org/engine/rotax-582dcdi) (registry code 55562, 2 cycle) (OpenAirDocs) - Category: Airplane, amateur-built - Serial number: CH2-1296-1544 - Airframe hours: 172 - Engines: Rotax 503 UL DCDI 52 horsepower reciprocating - Damage: Substantial damage - Flight: Personal, Part 91 - Operator: On File - Registered owner: Klemp Gregory J - Airworthiness certificate: Special, Experimental (Special) - Last inspection: Condition, March 5, 2011 - Departed: Neshkoro, WI - Destination: Neshkoro, WI ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 61; injuries: serious; private; airplane ratings: single-engine sea, single-engine land; medical: class 3, with waivers/limitations; last flight review October 5, 2010; seat: rear; flight hours: 3,000 total, 2,000 in this make and model ## Weather - Conditions: Visual (VMC), Day - Wind: calm - Visibility: 10 statute miles - Lowest ceiling: none ## 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 20110629011649A](https://openairdocs.org/incident/20110629011649A), Jun 29, 2011: Klemp Gregory J CHALLENGER II, Neshkoro, WI, Destroyed, 1 fatal. On June 29, 2011 at 1935 pilot [privacy data omitted] (broken rib and minor leg and neck soreness) was taking gordon sheveland (fatality) on a demo ride. At… ## Docket (16 files) The files NTSB released with the investigation on March 8, 2012, on NTSB's docket system: https://data.ntsb.gov/Docket?ProjectID=80949. 15.3 MB in all. - Record of Conversation - Pilot (item 1, .PDF, 54 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40364209&FileExtension=.PDF&FileName=Record%20of%20Conversation%20-%20Pilot-Master.PDF - Rotax Engine Pre-flight Checklist (item 2, .PDF, 70 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40364211&FileExtension=.PDF&FileName=Rotax%20Engine%20Pre-flight%20Checklist-Master.PDF - Excerpt of Maintenance Manual (item 3, .PDF, 231 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40364214&FileExtension=.PDF&FileName=Excerpt%20of%20Maintenance%20Manual-Master.PDF - Excerpt of Engine Operators Manual (item 4, .PDF, 621 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40364215&FileExtension=.PDF&FileName=Excerpt%20of%20Engine%20Operators%20Manual-Master.PDF - Periodical Maintenance Information (item 5, .PDF, 43 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40364287&FileExtension=.PDF&FileName=Periodical%20Maintenance%20Information-Master.PDF - Condition Inspection Logbook Entry (item 6, .PDF, 130 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40364282&FileExtension=.PDF&FileName=Condition%20Inspection%20Logbook%20Entry-Redacted.PDF - Excerpt of Engine Logbook (item 7, .PDF, 229 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40364288&FileExtension=.PDF&FileName=Excerpt%20of%20Engine%20Logbook-Redacted.PDF - Rotax Information (item 8, .PDF, 82 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40364216&FileExtension=.PDF&FileName=Rotax%20Information-Redacted.PDF - Toxicological Report (item 9, .PDF, 46 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40364217&FileExtension=.PDF&FileName=Toxicological%20Report-Redacted.PDF - Photo 1 - View of Main Wreckage in Terrain (item 10, .PDF, 3.2 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40364218&FileExtension=.PDF&FileName=Photo%201%20-%20View%20of%20Main%20Wreckage%20in%20Terrain-Master.PDF - Photo 2 - View of Main Wreckage (item 11, .PDF, 2.5 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40364219&FileExtension=.PDF&FileName=Photo%202%20-%20View%20of%20Main%20Wreckage-Master.PDF - Photo 3 - View of Engine and Propeller (item 12, .PDF, 2.2 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40364220&FileExtension=.PDF&FileName=Photo%203%20-%20View%20of%20Engine%20and%20Propeller-Master.PDF - Photo 4 - View of Engine (item 13, .PDF, 2.1 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40364221&FileExtension=.PDF&FileName=Photo%204%20-%20View%20of%20Engine-Master.PDF - Photo 5 - View of Broken V-Belt (item 14, .PDF, 1.3 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40364222&FileExtension=.PDF&FileName=Photo%205%20-%20View%20of%20Broken%20V-Belt-Master.PDF - Photo 6 - View of Piston Scoring (item 15, .PDF, 1.2 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40364223&FileExtension=.PDF&FileName=Photo%206%20-%20View%20of%20Piston%20Scoring-Master.PDF - Photo 7 - View of Piston Scoring (item 16, .PDF, 1.3 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40364224&FileExtension=.PDF&FileName=Photo%207%20-%20View%20of%20Piston%20Scoring-Master.PDF 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.