Pilot Debrief

PIPER PA 24-260 near Scottsdale, AZ — 2018-04-10

Final reportWPR18FA119
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Date
2018-04-10
Location
Scottsdale, AZ, USA
Airport
SDL
Aircraft
PIPER PA 24-260
Registration
N9456P
Category
Airplane
Highest injury
Fatal
Fatalities
6
Phase of flight
Takeoff roll

Probable cause

The flight instructor's failure to maintain airplane control during the initial climb as a result of the airplane being loaded above its maximum gross weight and beyond its aft center of gravity limits. Contributing to the accident was a degraded engine power output due to a preexisting engine cylinder intake valve spring failure, which further reduced the airplane's climb capability.

NTSB narrative

The airline transport pilot, student pilot, and four passengers departed on a cross-country fight with the airline transport pilot occupying the front right seat, the student pilot occupying the front left seat, and the four passengers occupying the two middle row and two aft row seats. Even though the student pilot was seated in the left seat, the investigation could not determine who was manipulating the flight controls when the accident occurred. Witnesses and airport surveillance camera video indicated that the airplane's wings were rocking during the departure and shortly after rotation. The controller asked if the airplane was experiencing any difficulties; according to the controller, the pilot responded, "we're good. We're just in training mode." One witness reported that the engine sounded as if it was not developing enough power. The last recorded radar data point indicated that the airplane's altitude was about 200 ft above ground level. A traffic camera, located about 0.5-mile northwest of the end of the runway, showed the airplane in a left bank turning left. As the turn progressed, the bank angle increased, and the airplane started to descend. The airplane's wings were nearly vertical before the airplane impacted terrain. A postcrash fire ensued. Evidence indicated that, at the time of departure, the airplane was 135 pounds over its maximum gross weight and was loaded 2.22 inches beyond its aft center of gravity (CG) limit. The CG is an important factor in flight performance. If the CG is too far aft, the airplane could rotate prematurely on takeoff, and longitudinal stability could be reduced. It is likely that during the initial climb, the pilot was unable to maintain airspeed which resulted in a loss of control. Postaccident examination of the engine revealed that the No. 3 cylinder intake outer valve spring was broken. The fracture surfaces had signatures consistent with fatigue growth before failure. The surface damage observed on the springs indicated that the failure had likely occurred at some point before the accident and had gone undetected. It is likely that the failure reduced the available engine power that, although not detectable during previous flights, was more critical with the overloaded condition of the accident flight. No other preimpact anomalies were noted that would have precluded normal operation of the engine and airframe. The inactive cocaine metabolite benzoylecgonine was found in the student pilot's blood specimens at fairly low or nondetectable concentrations and without any detection of cocaine, which indicated past and not immediate cocaine use. Although the timing of the student pilot's cocaine use could not be determined, cocaine has a very short half-life, so, unless the student pilot was a chronic user, this drug would have a negligible effect after 6 hours. Similarly, the detection of methylenedioxymethamphetamine (ecstasy) in the student pilot's urine but not blood specimens indicated past and not immediate use of this drug. Thus, the student pilot's cocaine and ecstasy use were not a factor in this accident.

Analysis

Primary failure mode
Loss of control
First missed decision gate
Pilot could have aborted takeoff due to engine power issues.

NTSB coding

Evidence available

  • Video
  • ADS-B / radar
  • 20 docket documents
View NTSB final reportView NTSB docket

Docket documents20

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