Electrical Failure During Initial Climb at Jerez Airport (EC-IYV)

Incident Overview and Aircraft Details On 14 January 2013, at 08:30 local time, a Piper PA-34-220T (registration EC-IYV, serial number 34-33113) operated by Flight Training Europe experienced an electrical anomaly during a commercial training flight at Jerez Airport in Cádiz. The aircraft was equipped with two Teledyne Continental Motors TSIO 360-KB10B engines and two Kelly Aerospace ALX 9525B alternators. The flight crew consisted of a 65-year-old commercial pilot with flight instructor qualifications and 16,630 total flight hours, and a 31-year-old student pilot with 287 total flight hours. Both individuals were uninjured, and the aircraft sustained no damage. ## Sequence of Events During engine start for a proficiency check, the student pilot encountered difficulties starting the left engine, which resulted in the aircraft battery becoming discharged. External power was used to successfully start both engines, beginning with the right engine. Pre-flight checks were completed normally, and engine and electrical indications were normal. During taxi, the crew observed that reducing engine power below 1,000 rpm caused the VOR No. 1 and ADF to lose indications and the communications display to flicker; increasing power restored all indications. The aircraft took off normally. After selecting the landing gear up, all navigation and communications screens turned off, and engine indicators dropped to zero. The landing gear position was not indicated, so the crew maintained a speed below 108 knots. The interphone communication was also lost, leading the crew to assume a total electrical failure. ## Recovery and Landing The crew reduced the electrical load. When the pitot tube heating was disconnected, instrument indications and radio communications were restored. The crew contacted the aerodrome tower to return to the airport, verified that the landing gear remained down and locked, and landed without further electrical anomalies. ## Investigation and Technical Findings The investigation found that the aircraft's battery was completely discharged. After replacement with a new battery, ground tests were satisfactory, and the problem did not recur. The removed battery showed no physical damage and passed a capacity test, indicating its condition was reversible. The operator conducted ground simulations using an alternator, voltage regulator, battery, electrical loads, and an ammeter. The tests demonstrated that with a charged battery, the system could handle loads exceeding the alternator's capacity. However, with a discharged battery, when external loads exceeded the alternator's production capacity—including the energy required to recharge the battery—the alternator collapsed because it could not maintain its electromagnetic field. This caused a system voltage drop and a false overcurrent indication. The alternator collapse persisted until the electrical load was reduced, power to the inductor winding was disconnected, and then reconnected. ## Analysis and Safety Actions The analysis confirmed that when electrical demand exceeded alternator capacity and a discharged battery could not supply additional energy, a voltage drop occurred, causing the alternators to collapse and display an overcurrent indication. The aircraft's emergency procedures for electrical overcurrent (maximum 60 A) instruct crews to turn the battery off, reduce load, and turn the battery back on if the overcurrent persists. The extended procedure in the flight manual notes that an abnormally high alternator output indication (more than 30 A above known loads) may be caused by a low or failed battery. The report noted that general aviation crews may misinterpret an overcurrent warning as an excess demand rather than insufficient electrical production, potentially associating it with alternator failure rather than a discharged battery. In this case, the experienced crew correctly identified and resolved the failure, returning to the airport and postponing the flight plan. Following the event, Flight Training Europe improved its operational procedures to prevent dispatching an aircraft that requires external power to start the engine due to a discharged battery, unless the battery is replaced with one in good condition.