NTSB Factual Report

HISTORY OF FLIGHT

On July 21, 2016, about 1114 central daylight time, a Piper PA 30 airplane, N7409Y, was destroyed following an in-flight breakup near Plainfield, Illinois. The commercial pilot was fatally injured. The airplane was registered to and operated by the pilot under the provisions of Title 14 Code of Federal Regulations Part 91. Day visual meteorological conditions were reported near the accident site about the time of the accident and no flight plan was filed for the flight. The personal flight originated from Upper Cumberland Regional Airport (SRB), near Sparta, Tennessee, about 0845, and was destined for Eagle River Union Airport (EGV), Eagle River, Wisconsin.

According to fueling records, the airplane was fueled with 73.61 gallons of 100 low lead aviation gasoline at SRB on July 21, 2016. The airplane taxied out for departure about 0841. Shortly after takeoff, the pilot established contact with a Federal Aviation Administration (FAA) air traffic controller and requested visual flight rules flight following to EGV. Flight following service availability is based on controller workload. The flight was issued a discrete transponder code (1647) and proceeded toward the destination. At 1039, the pilot established contact with the Chicago, Illinois, Air Route Traffic Control Center. At 1104, as the airplane neared Class B airspace, the controller terminated flight following services tofor the airplane, instructed the pilot to change the transponder code to VFR (1200), and provided another frequency on which the pilot could attempt to reinstate flight following. The pilot contacted the next controller at 1105 and provided his previously-assigned discrete transponder code of 1647. The controller could not identify the airplane using that code and provided another ATC frequency to the pilot. The next controller was also unable to identify the airplane using the 1647 transponder code and instructed the pilot to remain clear of the Class B airspace.

A radar performance study indicated that, until about 1108, the airplane was travelling on a heading about 320° (true) at an altitude of 8,500 ft mean sea level (msl) and a groundspeed about 150 kts. About 1108:23, the airplane initiated a climb, during which its equivalent airspeed (groundspeed adjusted for wind conditions) began to decrease and its angle of attack increased to nearly 20° nose up. The airplane reached 10,300 ft about 1111:10. Shortly thereafter, it reached its lowest equivalent airspeed about 48 knots, then entered a series of descending turns. The final radar target was recorded about 1112:37, at an altitude of 2,200 ft and an equivalent airspeed of 211 kts.

Witnesses saw sections of the airplane descend. Sections of the airplane impacted multiple locations in the Plainfield area, one of which caught fire and ignited a nearby building. No ground injuries were reported. Witnesses reported weather in the area consistent with a rapidly-forming thunderstorm.

PERSONNEL INFORMATION

The 58-year-old pilot held a FAA commercial pilot certificate with airplane multiengine land and instrument airplane ratings. He held private pilot privileges in single-engine land airplanes. His most recent FAA third-class medical certificate was issued on May 31, 2016, with limitations that the pilot "must wear lenses for distant, have glasses for near vision. Must wear corrective lenses, possess glasses for near/intermediate vision." The pilot reported on the application for that medical certificate that he had accumulated 976 total hours of flight experience and 5 hours the 6 months before the exam. A review of the pilot's recovered logbook indicated that he had accumulated 981.1 total hours of flight experience and that his most recent flight review was completed on April 15, 2015.

AIRCRAFT INFORMATION

N7409Y was a 1964 model Piper PA 30, Twin Comanche airplane with serial number 30-470. The Twin Comanche was an all-metal, multiengine airplane that incorporated a semimonocoque fuselage and empennage design. The airplane was equipped with fully cantilevered wings, wing flaps, and retractable tricycle landing gear. The airplane was powered by two Lycoming IO-320-B1A engines, each rated at 160 horsepower. (Left engine serial number: RL-1085-55; right engine serial number L-1054-55) The IO-320-B1A engine is a four-cylinder, 320 cubic-inch displacement, fuel injected, reciprocating engine. The engines each drove a Hartzell, 2-blade, single-acting, hydraulically operated, constant speed type propeller with feathering capability.

The airplane was modified with a fuel tank mounted in both wing nacelles in accordance with supplemental type certificate (STC) SA00356WI.

The airplane was also equipped with tip tanks in accordance with STC SA727WE. The Pilot's Operating Handbook (POH) supplement in reference to the tip tanks, in part, stated:

LIMITATIONS SECTION

Same as prescribed in appropriate F.A.A. approved

Airplane Flight Manual except:

A. Auxiliary wing tip tank fuel to be used in level

flight only.

B. When using auxiliary fuel, use wing tip tank fuel

first.

C. Maximum allowable gross weight 3725 lbs. Any weight

in excess of 3600 lbs. must consist of symmetrically

loaded fuel in the tip tanks.

D. Never exceed air speed limit of 230 MPH (red line).

A review of recovered maintenance records showed that the airplane's most recent annual inspection was completed on September 22, 2015. An airplane logbook endorsement, dated November 1, 2015, indicated that the airplane had repairs completed to include the replacement of its left side center wing leading edge skin and lower center wing skin, and replacement of its left aileron skin.

METEOROLOGICAL INFORMATION

According to records from Lockheed Martin Flight Service, the pilot requested a weather briefing for the flight to SRB, but did not obtain a weather briefing for the accident flight.

A National Transportation Safety Board (NTSB) Senior Meteorologist gathered weather data and produced a Weather Study in reference to this investigation. The study is appended to the docket material associated with this investigation. The study, in part, included local Aviation Routine Weather Reports (METAR) at the Joliet Regional Airport (JOT), near Joliet, Illinois.

At 0753, the Storm Prediction Center issued a Convective Outlook that identified "marginal" risk for the accident site, defined as, "isolated severe thunderstorms possible, limited in duration and/or coverage and/or intensity."

At 1115, the recorded weather at JOT included wind from 230° at 7 kts, visibility 10 statute miles, sky condition broken clouds at 2,100 ft, temperature 32° C, dew point 27° C, and an altimeter setting of 30.10 inches of mercury.

At 1135, the recorded weather at JOT included wind from 210° at 3 kts, visibility 10 statute miles, present weather thunderstorms in the vicinity, sky condition scattered clouds at 2,100 ft, broken clouds at 4,200 ft, broken clouds at 5,000 ft, temperature 31° C; dew point 27° C, and an altimeter setting of 30.10 inches of mercury.

The meteorologist discovered that local observation stations had a lightning detection system installed. The lightning detection sensor provides cloud-to-cloud, cloud-to-ground and cloud-to-air lighting detection. Publicly disseminated METARs from the local stations were made every 20 minutes, and lightning must be detected within the previous one minute of the report in order to trigger an appropriate thunderstorm and/or lightning indication in the publicly-disseminated METAR. No special reports are issued from these observation stations, though internal reports are generated every minute, which are available via radio and phone.

Weather imagery depicted relatively clear skies at the accident location about 20 minutes before the accident time. Cumulus-type clouds were recorded to the west through north of the accident location at 1052. Subsequent imagery identified cumulus type clouds over the accident location about the accident time. Weather radar imagery identified reflectivity features consistent with convection immediately adjacent to the airplane's position immediately before the accident time.

There were no Airmen's Meteorological Information advisories active for the accident location at the accident time below 25,000 ft and there were no convective or non-convective Significant Meteorological Information advisories active for the accident location at the accident time. There were no Center Weather Advisories (CWA) or Meteorological Impact Statements issued by the Center Weather Service Unit at the Chicago Air Route Traffic Control Center that were active for the area where the accident occurred at the accident time. However, at 1140, a CWA was issued for an isolated thunderstorm with a diameter of 20 miles about 9 miles east-southeast of JOT moving from 280° at 15 knots. There were no publicly-disseminated pilot reports made within 2 hours of the accident time and 50 miles of the accident location.

The 1000 North American Mesoscale (NAM) model sounding for the accident location was retrieved from the National Oceanic and Atmospheric Administration's (NOAA) Air Resources Laboratory. The sounding indicated the most-unstable Convective Available Potential Energy (CAPE) parameter was 4,207 Joules/kilogram (from 995 hPa). The maximum vertical velocity (MVV) for this atmosphere was calculated as 92 meters/second (about 18,100 ft per minute). Additionally, the Downdraft CAPE (DCAPE) was measured at 1,194 Joules/kilogram. CAPE is a measure of the amount of energy available for convection and is directly related to the maximum potential vertical speed within an updraft; higher values indicate greater potential for severe weather. A value of 471 Joules/kilogram would be considered relatively weak. The DCAPE can be used to estimate the potential strength of rain-cooled downdrafts within thunderstorm convection, and is similar to CAPE. Larger DCAPE values are associated with stronger downdrafts. A value of 736 Joules/kilogram would be considered a moderate value.

COMMUNICATIONS

Recording of communications from the Chicago Terminal Radar Approach Control facility were reviewed along with their transcripts. The transcripts are appended to the docket material associated with this investigation. Communication from one sector in the facility, in part, stated:

PILOT: Private approach, twin Comanche 7409 Yankee. Would you maintain 8,500?

CONTROLLER: Whoever's calling, ident.

PILOT: Twin Comanche 7409 Yankee with you, maintaining 8,500.

CONTROLLER: Contact Chicago departure, 126.62. Maintain VFR outside the Bravo.

PILOT: 126.62?

CONTROLLER: Yes.

PILOT: Roger.

Communication from another sector in the facility, in part, stated:

PILOT: (Unintelligible) 7409 Yankee. We're just checking in at 8,500.

CONTROLLER: All right. Who, what, say your location the VFR (phonetic) craft checking in.

PILOT: I'm just outside of the class, the airspace here, by Lewiston University.

CONTROLLER: Okay. Have I already talked to you?

PILOT: Negative. They told me to call you up. I'm just passing by to the west.

CONTROLLER: Okay. Did they assign you a code?

PILOT: 1647.

CONTROLLER: Okay. Well, they haven't told me anything about you. Just maintain (unintelligible) class Bravo. I'll get back to you.

PILOT: Roger.

That was the last recorded communication with the accident airplane.

WRECKAGE AND IMPACT INFORMATION

The main wreckage was located on a driveway about 328° and 2.65 nautical miles (nm) from the center of JOT on a heading about 315°. The impact angle of the fuselage with terrain was consistent with a nearly vertical descent. The fuselage, empennage, right engine, right wing, and inboard section of the left wing were discolored, deformed, charred, and melted, with sections consumed by fire. The empennage was found inverted. The right engine's propeller exhibited chordwise abrasion. The nose landing gear jackscrew position was consistent with the gear retracted position.

Sections of fiberglass and aluminum consistent with cowling material were found about 108° and 0.82 nm from the main wreckage. An outboard section of the left wing was found near an access road to a parking lot about 144° and 0.44 nm from the main wreckage site. The left fuel tank was found about 181° and 0.41 nm from the main wreckage site. The left propeller cylinder and a section of its propeller dome and cap were found about 185° and 0.36 nm from the main wreckage site. The left propeller, which had a separated section of its crankshaft attached to it, was found about 199° and 0.35 nm from the main wreckage site. The left engine was found about 204° and 0.24 nm from the main wreckage site.

Disassembly examinations of the two propellers were conducted by the propeller manufacturer's safety representative under supervision of the NTSB investigator in charge. The two right engine propeller blades exhibited chordwise abrasions on both blades; one blade had a fractured tip. A preload plate witness mark suggested a blade angle of 37° at the time of impact. Damage to the right propeller was consistent with high impact forces. The two blades from the left propeller did not exhibit chordwise or rotational witness marks; one of the blades exhibited a hole. A preload plate witness mark suggested a blade angle of 25° at the time of initial impact. Damage to the left propeller was consistent with inflight separation and high impact forces. No preimpact anomalies were detected that would have precluded operation of the propellers.

Disassembly examinations of the two engines were conducted by the engine manufacturer's safety representative under supervision of the NTSB investigator in charge. Examination of the left engine revealed that the crankcase nose was fractured across its front main bearing saddle. The front main bearing shells remained in place. The engine could not be rotated by means of a tool inserted in the vacuum pump drive pad and was further disassembled. No damage to the crankshaft was noted aft of the front main bearing journal and the crankshaft gear was secure. The front main bearing shells were distorted where the front portion of the crankshaft departed the engine. No damage was noted to the other main bearing shells. The connecting rods were free to rotate on the crankshaft rod journals. The connecting rods and their bearings, camshaft, cam followers, cylinders, piston, and piston rings did not exhibit any preimpact anomalies. Oil was observed in the engine. No metallic debris was observed in the oil suction screen or on the oil filter media. The fuel injector servo was separated from the left engine. The servo was partially disassembled and its rubber diaphragms did not exhibit any anomalies. The servo fuel inlet screen was absent of debris. The flow divider was impact separated from the engine. The divider was partially disassembled and no debris was found internally; there was no damage to the rubber diaphragm. The fuel injector nozzles remained attached to the engine. Nozzle No. 1 was fractured. Nozzle Nos. 2 and 3 were undamaged and unobstructed. Nozzle No. 4 was bent. The left engine-driven fuel pump remained attached to the engine and was impact damaged. Disassembly of the pump revealed no anomalies. Liquid with an odor consistent with aviation gasoline was observed in the engine-driven fuel pump, the fuel injector servo, and the hose from the servo to the flow divider.

The left engine's left magneto remained partially attached to the engine and was impact damaged. The magneto could be rotated by hand and produced spark from all ignition towers. The left engine's right magneto was separated from the engine and its case was fractured. It was difficult to rotate by hand and did not produce spark.

All sparkplugs remained attached to the left engine and all their electrodes were undamaged. The No. 4 top and bottom sparkplugs exhibited reddish colored debris in their electrode wells. All other left engine sparkplugs exhibited normal combustion coloration when compared to a Champion Aviation Check-A-Plug Card.

The left engine's vacuum pump was impact damaged and separated from the engine. The composite drive coupling was in place. The carbon colored rotor and on

NTSB Probable Cause

The pilot's failure to maintain airplane control during an en route climb near convective activity, which resulted in an aerodynamic stall, an uncontrolled descent, and a subsequent in-flight breakup due to an exceedance of the airplane's design load limitations.