N8223WPiper PA-28-180 · 1965

On August 23, 2013, about 1838 Pacific daylight time, a Piper PA-28-180 airplane, N8223W, was substantially damaged when it impacted trees and terrain shortly after takeoff from runway 20 at Sacramento Executive Airport (SAC), Sacramento, California. The private pilot and certified flight instructor (CFI) received serious injuries. The airplane was operated by Capitol Flying, Inc., and the instructional flight was conducted under the provisions of Title 14 Code of Federal Regulations Part 91. Visual meteorological conditions prevailed, and no Federal Aviation Administration (FAA) flight plan was filed for the flight.

According to the pilot, he had recently purchased a membership share in Capitol Flying, Inc., in order to utilize their airplanes. He enlisted the CFI to provide a checkout in the accident airplane, in order to comply with club membership requirements. The accident flight was their second flight in the airplane. They planned to conduct some airwork, fly to University airport (EDU), Davis, California, conduct some pattern work, then return to SAC. Preflight inspection detected no anomalies, and the airplane had about 36 gallons of fuel on board.

Engine start, taxi out to runway 20, engine runup, and the takeoff roll were all normal. Shortly after takeoff, the engine "sputtered" momentarily, but restored to full/normal power for a very brief time. Both the pilot and the CFI believed that this occurred at an altitude of about 500 to 600 feet above ground level (agl). Very shortly thereafter, the engine stopped producing sufficient power for flight, and was running "roughly." In response to the CFI's instruction, the pilot moved the fuel selector handle to switch fuel tanks. The pilot and CFI verified that the throttle and mixture controls were in their full forward positions, but no improvement was noted, and the airplane continued to descend. Neither pilot could recall whether they attempted to apply carburetor heat or not. They turned the airplane to the left to attempt to land in a clear area on a golf course, but the airplane struck intervening trees. Golfers on the course extracted the pilot and CFI from the airplane, tended to them, and summoned first aid. Neither the pilot nor the CFI recalled any events between the tree strikes and finding themselves in the ambulances.

Pilot Under Instruction

The pilot held a private pilot certificate with an airplane single-engine land rating. He obtained that certificate in October 2011. His most recent FAA second-class medical certificate was issued in August 2013. The pilot reported that he had a total flight experience of about 74 hours. His only prior experience in the accident airplane make and model was the previous flight a week earlier; the duration of that flight was approximately 1/2 hour.

Certified Flight Instructor

The CFI held instructor ratings for airplane single- and multi-engine land, and instrument airplane. He estimated that he had a total of about 7,000 hours of flight experience, including about 500 hours in the accident airplane make and model. His most recent FAA first-class medical certificate was issued in April 2013.

FAA information indicated that the airplane was manufactured in 1965 as Piper serial number 28-2356. It was a low-wing, fixed gear tricycle configuration, and was equipped with a Lycoming O-360 series engine. The airplane was not equipped with shoulder harnesses. According to the airplane flight log sheet, the airplane had been flown about 3.5 hours in the week preceding the accident. The accident flight was the first flight since August 20, 2013.

The maintenance records indicated that the most recent annual inspection was completed in March 2013, when the airframe had a total time of about 5,714 hours, and that the tachometer registered about 4,476 hours. At the time of that annual inspection, the engine had accumulated about 1,430 hours since overhaul. The only logged engine maintenance subsequent to the most recent annual inspection was an oil change on June 15, 2013, at a tachometer time of 4,528 hours, and an engine total time of about 1,482 hours

The SAC 1853 automated weather observation included winds from 200 degrees at 7 knots, visibility 10 miles, clear skies, temperature 27 degrees C, dew point 11 degrees C, and an altimeter setting of 29.74 inches of mercury.

Temperature and dew point values for the approximate time of the accident indicated that the relative humidity was approximately 35 percent. When the intersection of the two temperature values was located on a chart that depicted carburetor ice envelopes, the point was in the region of the chart denoted as "Serious Icing at Glide Power," near the boundary of the region denoted as "Icing - Glide and Cruise Power."

FAA information indicated that the airplane was manufactured in 1965 as Piper serial number 28-2356. It was a low-wing, fixed gear tricycle configuration, and was equipped with a Lycoming O-360 series engine. The airplane was not equipped with shoulder harnesses. According to the airplane flight log sheet, the airplane had been flown about 3.5 hours in the week preceding the accident. The accident flight was the first flight since August 20, 2013.

The maintenance records indicated that the most recent annual inspection was completed in March 2013, when the airframe had a total time of about 5,714 hours, and that the tachometer registered about 4,476 hours. At the time of that annual inspection, the engine had accumulated about 1,430 hours since overhaul. The only logged engine maintenance subsequent to the most recent annual inspection was an oil change on June 15, 2013, at a tachometer time of 4,528 hours, and an engine total time of about 1,482 hours

The wreckage was located on a golf course that was situated adjacent to the southern boundary of SAC. The fuselage came to rest inverted. Both wings had fracture-separated during the impact sequence, but the fuselage and cabin remained essentially intact. The engine remained attached to its mount, which remained partially attached to the fuselage. There was no fire, but firefighters did spray the wreckage with water due to the fact that the airplane was leaking fuel. The site was photographically documented by first responders, and the wreckage was then recovered to a secure facility for detailed examination.

Representatives from the NTSB, the FAA, Lycoming Engines, and Piper Aircraft conducted a detailed examination of the wreckage in December 2013. All major components of the airframe and engine were accounted for. Flight control continuity was established for all primary and secondary flight controls. The flaps were determined to be up/retracted at impact, and the stabilator (pitch) trim was in the 'neutral' setting.

The engine primer control was found in the 'in and locked' position. The throttle, mixture, and carburetor heat controls were all found in their full forward positions, and were securely attached at their respective control arms in the engine compartment. Damage to the carburetor heat airbox and actuation cable was consistent with the carburetor heat in the OFF (heat not applied) setting at impact.

The ignition switch was found in the OFF position, and the key was absent. The master and fuel pump toggle switches were found to be in their OFF (switch down) positions, but several other nearby toggle switches on the same sub-panel were found in their respective ON (switch up) positions. The fuel selector handle was found in the OFF position. One first responder reported to the news media that he had turned the fuel selector to OFF, but the investigation was unable to determine whether any other switches or controls had been moved, either intentionally or unintentionally, by first responders.

The airplane fuel system, including tanks, screens, lines, valves, and pump did not exhibit any anomalies that could not be attributed to impact. The gascolator bowl was partially separated from its housing, but the fuselage was damaged in this region, and the bowl's loose condition was consistent with impact damage. No fuel staining indicative of a loose bowl during flight was observed. Fuel selector valve functionality was verified.

Visual examination of the engine did not reveal any evidence of pre-impact mechanical failure or fire. The engine sustained moderate impact damage to its forward lower region, including the exhaust system, baffling, and alternator.

The bottom spark plugs were removed, and the crankshaft was rotated manually. The crankshaft rotated freely in both directions. "Thumb" compressions were observed in proper sequence on all four cylinders. The entire valve train was observed to operate in proper sequence, and was free of any pre-impact mechanical malfunction. Mechanical continuity was confirmed for the crankshaft, pistons, and accessory section via crankshaft rotation. Clean, uncontaminated oil was observed at all four rockerbox areas.

The combustion chambers and valves of all cylinders were undamaged, with no evidence of foreign object ingestion, valve-piston contact, or detonation. The gas path and combustion signatures at the spark plugs, combustion chambers, and exhaust system components displayed coloration consistent with normal operation. No oil residue was observed in the exhaust system gas path.

Both magnetos remained securely attached to their respective mounting pads, and were undamaged. Magneto to engine timing could not be determined due to the separation of the flywheel and propeller, but the two magnetos were timed to within 1 degree of each other. The "P" lead of each magneto remained securely attached. Each magneto produced sparks at all towers during manual rotation. All ignition harness leads were securely attached to their respective magneto towers.

All engine compartment fuel lines were found to be secure at their respective engine fittings, but those lines had been fracture-separated by the impact separation of the wings. The engine driven fuel pump remained attached to its engine mounting pad, and was undamaged. The pump was removed and opened for examination. The pump was free of internal mechanical damage or obstruction to flow, and the diaphragm was intact. Water was observed within the pump; this was attributed to the fractured fuel lines and the fact that first responders sprayed with wreckage with water as a fire-prevention effort.

The carburetor remained attached to the engine. The fuel bowl and accelerator pump well were free of visible contaminants. The float assembly was properly attached, and freedom of motion was verified. The floats exhibited no evidence of rubbing against the bowl walls. All carburetor internal locking tabs and safety devices were in place and properly secured.

The propeller and hub assembly was fracture-separated from the engine at the crankshaft; the propeller flange remained intact and securely attached to the hub. Propeller blade damage was consistent with little or no power at impact.

Carburetor Heat and Emergency Procedures Guidance

Review of the "Normal Procedures Checklist" and the "Emergency Procedures Checklist" that were recovered from the airplane revealed that the checklists were not published by Piper, and that they were designated for a PA-28R-180 airplane, which is equipped with a fuel-injected engine. Since the PA-28R-180 was not equipped with carburetor heat, the checklists' "Normal" and "Engine Failure" procedures did not contain any references to, or procedures for, application of carburetor heat.

Review of the "Ground Check" portion of Section III (Operating Instructions) of the Piper-produced Owner's Handbook (OH) for the PA-28-180 contained the statement "Carburetor heat should also be checked prior to take-off to be sure that the control is operating properly and to clear any ice which may have formed during taxiing." The OH did not contain any amplifying or clarifying information regarding carburetor icing during taxi.

Review of the Piper OH and the FAA-approved AFM revealed that neither document contained any guidance or checklists regarding emergency procedures, including loss of engine power. According to representatives from Piper and the FAA, the OH and AFM were in compliance with the applicable certification regulations.

Cockpit Fuel Selector

The cockpit fuel selector had three settings; a detented position for each (left and right) tank, plus a 90-degree arc for the OFF position. The handle could be rotated through 360 degrees in either direction. The original handle and placard design was ambiguous with regard to proper use/setting by pilots; a pilot could inadvertently select the OFF position while interpreting the selected setting as being for the left or right tank.

In 1971 and 1972, Piper issued two separate Service Letters (SL 588 and SL590, respectively), which recommended modifications to the cockpit fuel selector to make it less susceptible to inadvertent incorrect operation. The basic contents of those two SLs were integrated into the 1986 Piper Service Bulletin (SB) 840 entitled "Fuel Selector Valve Cover Replacement. SB840 called for the replacement of the existing handle and placard with redesigned versions, and Piper designated SB840 as "mandatory."

According to SB840, the purpose was "To announce the availability of a new fuel selector valve cover assembly and mating handle, which reduces the possibility of pilot mismanagement of the fuel system through inadvertent selection to the "OFF" position, resulting in power interruption or stoppage." SB840 compliance time was specified as "To coincide with next regularly scheduled maintenance event, but not to exceed the next 25 hours time in service."

Although SB840 was applicable to the accident airplane, it was never accomplished on that airplane. In November 2013 (subsequent to the accident), SB840 was reissued as SB840A to revise certain Piper part numbers.

On August 20, 2013, the FAA issued a Notice of Proposed Rulemaking which proposed an Airworthiness Directive based on SB840. In June 2014, the FAA withdrew that proposed AD, due to an FAA re-evaluation that determined that "an unsafe condition does not exist that would warrant AD action."

Fuel Starvation Tests

Because the installed fuel selector was subject to inadvertent improper operation by pilots, and was the subject of a Piper service bulletin, the investigation attempted to locate data regarding how long an engine would operate once the fuel was shut off. Such testing was not required for FAA certification. Piper did not provide any data on this topic, and searches for relevant or similar data yielded very sparse results, none of which were for a PA-28 with an O-360 engine. With the assistance of the FAA and another flight school, a dedicated test using a PA-28 equipped with an IO-360 engine was able to be accomplished. However, because there was no data from an O-360 equipped PA-28, and the previous and new results displayed significant data scatter, the results were deemed to be inapplicable for this investigation.

No tests were conducted for a partially mis-set selector valve, where the valve was positioned so that the valve ports were partially, but not completely, aligned. In such a mis-set position, the port misalignment would limit the maximum fuel flow, and the maximum fuel flow would be governed by the degree of misalignment. A misaligned port could permit sufficient fuel flow to allow the engine to run continuously at a low power setting, but not permit sufficient fuel flow to sustain continuous high-power operation, such as for takeoff or climbout. In such a case, the fuel in the carburetor bowl would provide a small reserve to allow high power operation for a limited time, until that fuel was depleted, when the misaligned port then becomes the limiting factor for fuel flow.

A copy of the audio recording between the SAC air traffic control tower and the airplane was obtained and reviewed. Approximately 6 minutes 20 seconds elapsed between the time the pilots requested taxi clearance and the time they requested takeoff clearance. Due to landing traffic, another 2 minutes elapsed before the airplane was issued a takeoff clearance. One minute 54 seconds after the takeoff clearance was issued, the tower controller queried the flight as to whether it needed assistance, due to his observation of its turnback and descent. No response was recorded from the airplane. Review of the recording revealed that after the pilots acknowledged the takeoff clearance, there were no other transmissions from the airplane.