Wednesday, November 6, 2019

Aerodynamic Stall / Spin: Wheeler Express, N246TM; fatal accident occurred August 19, 2017 near Madras Municipal Airport (S33), Jefferson County, Oregon

Mark Rich with the plane he built from a kit and flew for decades.



The National Transportation Safety Board traveled to the scene of this accident.

Additional Participating Entities:

Federal Aviation Administration / Flight Standards District Office; Hillsboro, Oregon
Teledyne Continental Motors; Mobile, Alabama

Aviation Accident Factual Report - National Transportation Safety Board: https://app.ntsb.gov/pdf


Investigation Docket - National Transportation Safety Board: https://dms.ntsb.gov/pubdms 
 
http://registry.faa.gov/N246TM


Location: Madras, OR
Accident Number: WPR17FA185
Date & Time: 08/19/2017, 1352 PDT
Registration: N246TM
Aircraft: Rich Wheeler Express CT
Aircraft Damage: Destroyed
Defining Event: Aerodynamic stall/spin
Injuries: 1 Fatal
Flight Conducted Under: Part 91: General Aviation - Personal 

On August 19, 2017, about 1352 Pacific daylight time, a Rich Wheeler Express CT, N246TM, impacted the wall of a canyon while on approach to land at Madras Municipal Airport (S33), Madras, Oregon. The private pilot sustained fatal injuries; the airplane was destroyed. The airplane was owned by the pilot who was operating it as a Title 14 Code of Federal Regulations Part 91 personal flight. Visual meteorological conditions prevailed and no flight plan had been filed for the cross-country flight, which originated from San Carlos airport (SQL), San Carlos, California, with a final destination of S33.

The pilot was planning to camp at Madras and participate in the Oregon Solarfest, where activities were being held for the viewing of the solar eclipse. The pilot submitted a reservation request and payment to the Madras airport operations on July 22, 2017, indicating that he intended to arrive on August 19 at 1400 and depart on August 21.

A NOTAM was in effect at the time of the accident that provided instructions to pilots regarding arrival procedures they must follow to land at the Madras airport during the Solarfest. A Non−Federal Contract Tower (NFCT) was contracted by the normally non-towered airport to provide air traffic control services to help facilitate the increased traffic.

The NOTAM instructed pilots that all arrivals must be conducted at the time of their assigned reservation and via the routes depicted in the NOTAM unless otherwise instructed by the controllers (see figure 1). When arriving from the south, the NOTAM stated that pilots should perform the "Cove Entry," which required reporting over the Cove Palisades State Park (COVE) and flying north to Lake Simtustus Resort (RESORT), then continuing inbound toward the airport (east) and entering a left downwind for runway 34 (south).

Figure 01: NOTAM Instructional Picture


According to the controller working at the tower at the time of the accident, the accident pilot established contact with the tower over COVE and was instructed to report his position when he was over RESORT. Several minutes later, after other traffic departed, the controller modified the pilot's instructions and told him to proceed to a 3-mile final to runway 34. After a few minutes, the controller requested that the pilot report his position, to which he responded that he was on a 3-mile left base to runway 34. The controller cleared him to land and observed a plume of smoke shortly thereafter.

Witnesses located near the airport, stated that they observed the airplane make a steep left turn with the wings perpendicular to the terrain. The airplane then dove toward the ground in a nose-low, near-vertical descent.


Mark Rich

Pilot Information

Certificate: Private
Age: 58, Male
Airplane Rating(s): Single-engine Land
Seat Occupied: Left
Other Aircraft Rating(s): None
Restraint Used:
Instrument Rating(s): None
Second Pilot Present:No 
Instructor Rating(s): None
Toxicology Performed: Yes
Medical Certification: Class 3 With Waivers/Limitations
Last FAA Medical Exam: 10/31/2016
Occupational Pilot: No
Last Flight Review or Equivalent:
Flight Time: (Estimated) 612 hours (Total, all aircraft) 

The pilot, age 58, held a private pilot certificate issued in January 2012 with ratings for airplane single-engine land and instrument airplane. He held a third-class Federal Aviation Administration (FAA) airman medical certificate issued in October 2016, with the limitation that he must have glasses available for near vision. On the application for that medical certificate, he reported a total flight time of 612 hours. The pilot's personal flight records were not recovered.



Aircraft and Owner/Operator Information

Aircraft Make: Rich
Registration:N246TM 
Model/Series: Wheeler Express CT
Aircraft Category: Airplane
Year of Manufacture: 2002
Amateur Built: Yes
Airworthiness Certificate: Experimental
Serial Number: 145
Landing Gear Type: Tricycle
Seats: 4
Date/Type of Last Inspection:  Unknown
Certified Max Gross Wt.:
Time Since Last Inspection:
Engines:  Reciprocating
Airframe Total Time:
Engine Manufacturer: Teledyne Continental Motors
ELT: Installed
Engine Model/Series: IO540-K1G5
Registered Owner: On file
Rated Power: 300 hp
Operator: On file
Operating Certificate(s) Held: None

The Wheeler Express CT is an experimental, amateur-built airplane that is sold as a kit. The composite construction airplane was a four-place, low-wing, tricycle landing gear monoplane equipped with a 'cruciform' (mid-mounted horizontal stabilizer) tail. The pilot completed the build in 2002 as the original design. The accident airplane, serial number 145, received a special airworthiness certificate in the experimental category in August 2002. The airplane was equipped with a Lycoming IO-540-KIG5 engine, serial number L-17422-48A, rated at 235 shaft horsepower.

The maintenance logbooks were not recovered. The airplane was last fueled before departure from San Carlos with the addition of 58.9 gallons of 100LL aviation fuel.

Airplane Design

In 1991, Wheeler Express sent a letter to owners addressing the possibility of deep stalls occurring in the tail; the letter stated that if the builder installs the tail correctly there would not be abnormal stall characteristics.

Wheeler Express was then purchased by Express Design Inc (EDI), who sent a letter in 1995 to builders and owners detailing a report about the design and aerodynamic characteristics of the cruciform tail. In pertinent part, it stated:

At the forward CG, flaps down, approach condition, a larger tail requires much less up elevator to trim. Very small (and therefore heavily loaded) tails may stall on approach and turbulent conditions or upon crossing another airplane's wake (or its own wake in a turn). If the tail stalls in the approach condition, rapid action must be taken to avoid diving straight into the ground…

We believe therefore that because the Express CT can experience uncommitted pitch down motion under certain flight conditions, that certain actions are required by EDI and by Express CT builders and owners specifically… Because certain flight conditions such as turbulent air can cause the uncommitted pitch down without pilot involvement, EDI believes that each owner of an Express CT kit for aircraft should seriously consider updating their kit or airplane with the S-90 tail update available from EDI.

A Wheeler Express performance report, sponsored and funded by the FAA and the Experimental Aircraft Association (EAA), was completed in 1997. The performance report identified that the 'cruciform' tail (mid-mounted horizontal stabilizer), wide tapering fuselage, and highly swept vertical stabilizer combined to produce low yaw stability. In part, it stated:

The tail power seemed to be adequate for most regimes of flight, however, during post stall and high yaw maneuvering the horizontal/elevators seemed to have inadequate effect. This seemed to be caused by blanking of the horizontal tail and elevators by the vertical stabilizer at the highly yawed condition. More testing is definitely in order to study the flow field around the tail in this situation and to develop improved tail effectiveness.

Meteorological Information and Flight Plan

Conditions at Accident Site: Visual Conditions
Condition of Light: Day
Observation Facility, Elevation: KS33, 2436 ft msl
Distance from Accident Site: 1 Nautical Miles
Observation Time: 2055 UTC
Direction from Accident Site: 360°
Lowest Cloud Condition: Clear
Visibility:  10 Miles
Lowest Ceiling: None
Visibility (RVR):
Wind Speed/Gusts: Light and Variable /
Turbulence Type Forecast/Actual:
Wind Direction: Variable
Turbulence Severity Forecast/Actual:
Altimeter Setting: 30.14 inches Hg
Temperature/Dew Point: 24°C / 5°C
Precipitation and Obscuration: No Obscuration; No Precipitation
Departure Point: San Carlos, CA (SQL)
Type of Flight Plan Filed: None
Destination: Madras, OR (S33)
Type of Clearance: None
Departure Time:  PDT
Type of Airspace:

The 1355 weather observation at S33 included: clear sky, 10 miles visibility, temperature 75°F, dew point 41°F, and altimeter setting of 30.15 inches of mercury.

Airport Information

Airport: MADRAS MUNICIPAL (S33)
Runway Surface Type: Asphalt
Airport Elevation: 2436 ft
Runway Surface Condition: Dry
Runway Used: 34
IFR Approach:None 
Runway Length/Width: 5089 ft / 75 ft
VFR Approach/Landing: Stop and Go; Straight-in 

Madras Municipal Airport was located at an elevation of 2,436 ft mean sea level and did not have a permanent control tower. The airport was equipped with two asphalt runways, designated 16/34 and 04/22. The active runway at the time of the accident was 16/34, which measured 5,089 ft long and 75 ft wide.

Wreckage and Impact Information

Crew Injuries: 1 Fatal
Aircraft Damage: Destroyed
Passenger Injuries: N/A
Aircraft Fire: On-Ground
Ground Injuries: N/A
Aircraft Explosion:None 
Total Injuries: 1 Fatal
Latitude, Longitude: 44.643056, -121.164444 

The accident site was located on the north-facing slope of a canyon comprised of soft dirt and trees. The wreckage was about 1.1 nautical miles from the approach end of runway 34 on a bearing of 025° (see figure 2).

Figure 02: Wreckage Location

The first identified points of contact were freshly-severed tree limbs adjacent to the main wreckage. The tree was located in a slight ravine in the ebb of the canyon wall. The debris field was primarily contained in the area of the main wreckage on a 60-70° slope.

The main wreckage sustained severe thermal damage and comprised the outboard right wing, empennage, engine, and the charred remnants of the fuselage. The cabin was completely consumed by fire.

The inboard right wing was located upslope of the engine and was identified by the shape of the wingtip and a small blue/green shard of material embedded in the navigation light area. The left wing was downslope of the engine toward the ravine. Under the wing were parts of the cockpit area and instrument panel, identified by the seat frames, rudder pedals, and burned remnants of the radios.

The engine came to rest on its left side with the Nos. 2, 4, and 6 cylinders completely imbedded in the dirt (see figure 3). A portion of one propeller blade was visible and the tip had melted. The propeller remained attached to the engine at the crankshaft flange. The spinner was bent around the hub and the bottom blade was broken free from the hub. The empennage was thermally destroyed and only portions of the flight controls were identifiable. The tail section was located in the ravine at the bottom of the debris field (about 15 ft from the engine).

Figure 03: Engine at Accident Site

Examination of the airframe revealed that the control materials constructed of steel were thermally damaged and a majority of the airplane that was composite material or aluminum was consumed by fire.

Pitch control was accomplished by two control columns connected to a mixing assembly, which continued aft via a series of two steel rods and two steel tubes running centerline to the elevators (a total of six rod end bearings were used in the assembly). Four rod end bearings exhibited signs of damage from overload. Two rod end bearings, both of which connected to the same steel bellcrank, exhibited no signs of overload or elongation and were lacking attachment hardware.

The aforementioned two rod ends were shipped to the NTSB Materials Laboratory for analysis. No evidence or markings consistent with the presence of fastening hardware were observed in either bearing bore. Because of the severe thermal damage to the wreckage, it could not be determined if the absence of material was due to it not being fastened at the time of impact or if the material was thermally consumed after impact.

Rotation of the engine was not possible due to binding of various components as a result of impact damage; compression could not be obtained. The cylinder combustion chambers were examined upon removal of the Nos. 1, 3, and 5 cylinders and borescope examination of the remaining cylinders. The combustion chambers remained mechanically undamaged and there was no evidence of foreign object ingestion or detonation. The valves were intact and undamaged. There was no evidence of valve-to-piston-face contact. The gas path and combustion signatures observed at the spark plugs, combustion chambers, and exhaust system components displayed coloration consistent with normal operation.

Ignition system continuity could not be established due to thermal damage. The engine oil sump was crushed upward against the internal engine components.

Examination of the McCauley propeller, model B3D32C417-C, serial number 900150, revealed that all blades sustained thermal damage. Blade 1 was broken free with leading edge polishing, chordwise scratches, and twisting. Blade 2 was loose in the hub with its tip melted away. Blade 3 was bent aft at its tip.

Examination of the airframe and engine revealed no evidence of mechanical malfunctions or failures that would have precluded normal operation. A detailed examination report is contained in the public docket for this accident. 

Medical And Pathological Information

The Jefferson County Office of the Medical Examiner, Clackamas, Oregon, performed an autopsy on the pilot. The cause of death was listed as multiple blunt force traumatic injuries.

Toxicology testing performed at the FAA Forensic Sciences Laboratory identified evidence of putrefaction in the specimens received. 32 (mg/dL, mg/hg) of ethanol was detected in muscle tissue, no ethanol was detected in brain specimens, consistent with postmortem production. No drugs were detected in lung specimens.

Additional Information

A similarly-equipped Wheeler Express was involved in a fatal accident on July 27, 2015 (NTSB case ID CEN15FA321). A review of onboard flight data revealed that the airplane maneuvered into a nose-high attitude while in a steep, right turn. As the airspeed decelerated below stall speed and the turn steepened, the airplane pitched nose down and entered a prolonged, right-turning spin until ground impact.

4 comments:

Anonymous said...

Dont think I would own something with those control issues

Anonymous said...

Why would they continue to produce such a design with the obvious inbuilt design faults that were already known ? high set tails are bad enough and known to have deep stall characteristics but this aircraft is obviously not right aerodynamically,perhaps this sad crash will enable vital modifications to be made.

Fig Bar Inspector said...

Looks like the kit maker realized the inherent problems with the high tail and strongly suggested an upgrade to minimize this design flaw. I pray that FAA makes it mandatory for aircraft owners to take on this much-needed upgrade. I don't know if the FAA is in the financing business but a small loan from them would go a long way for this safety modification.

gretnabear said...

Rich's Flight Time was an (Estimated) 612 hours in all aircraft. He completed his kit in 2002, thus if most of those hours were in his acft, it possibly involved hundreds of take-offs and landings without incident. Can we 'assume' Rich did not purchased / modtify his Express CT with the S-90 tail available from EDI?

https://www.express-builder.com/viewtopic.php?t=223
"After the company went bankrupt in the late 90s, some builders with partial kits got together to copy parts and finish their airplanes. This bred the version called the Auriga, and then the S90. Basically for your needs, if it is a CT, it has the smaller tail. If it has the conventional stab placement, it should have a larger tail."
and
"The CT tail has a stab about 8.5 feet long- IE wide. The Auriga made it about a foot longer and a wider chord- but I dont have time right now to see if I have that manual for exact numbers. I think I read before that it increased the tail area by 15%.The new kits are pretty much the same length tail as the Auriga"