Flight History
On 22 October 2016, a Piper PA-28RT-201T Turbo Arrow, registration HB-PGF, operated by Flugschule Basel AG, departed Basel-Mulhouse Airport (LFSB) at 10:59 local time for a planned flight to Samedan (LSZS) with two passengers and a pilot. The aircraft had been refueled for the flight, and standard pre-flight checks were performed.
The flight initially proceeded under instrument flight rules (IFR) to the Willisau radio beacon, where the pilot switched to visual flight rules (VFR) and reported to Zurich Info. The aircraft flew over Lucerne and south of the Walensee toward the Rhine valley.
At 12:02, approximately 12 km south of Chur at an altitude of 10,100 ft AMSL, the engine suddenly lost power, accompanied by vibrations and a rattling noise from the engine compartment. Manifold pressure dropped from about 30 inHg to between 15 and 20 inHg. The pilot executed a 180-degree turn to the right to avoid mountainous terrain and performed engine failure procedures. The engine continued to produce reduced power. The pilot switched off the electric fuel pump and found that throttle movement did not alter engine performance.
At 12:03:07, the pilot informed Zurich Info of the engine problems and declared an intention to divert to St. Gallen-Altenrhein (LSZR). Bad Ragaz was considered but ruled out due to its short runway and steep approach. At 12:06:09, the pilot declared an emergency. The aircraft maintained an indicated airspeed of about 90 kt with a descent rate of approximately 200 ft/min. The pilot believed this would allow reaching St. Gallen-Altenrhein with sufficient altitude, with the option of a landing in the Rhine valley if needed.
After a frequency change to Zurich Delta at 12:06:38, the pilot confirmed visual flight conditions at St. Gallen-Altenrhein. The aircraft entered the control zone over reporting point Sierra, executed a direct approach, and landed normally on runway 28 at 12:28:11. The fire service, on standby, followed the aircraft to the north apron, where the pilot shut down the engine. The fire service reported an unusual rattling engine noise heard during final approach.
Aircraft Information
The aircraft was a Piper PA-28RT-201T (Turbo Arrow IV), a single-engine, four-seat, low-wing monoplane with a T-tail and retractable landing gear. It was powered by a Continental Motors TSIO-360-FB1B engine rated at 200 hp. The airframe had accumulated 9,347 hours and 10 minutes time since new (TSN), and the engine had 716 hours and 4 minutes TSN. Mass and center of gravity were within permissible limits.
Weather
At the time of the incident, the weather was dry with good visibility. A light southerly wind prevailed along the Alpine valleys, with winds aloft at 10,000 ft AMSL from 250 degrees at 10-15 kt. Cloud cover consisted of 3/8 altocumulus at 20,000 ft AMSL. Visibility was 20 km. Temperature at 10,000 ft was -7°C, dew point -17°C. The QNH was 1015 hPa. The sky was daylight, with the sun at an azimuth of 163 degrees and an elevation of 30 degrees.
Maintenance History
The engine underwent a complete overhaul by the manufacturer on 22 May 2014 and was installed on 16 June 2014. On 26 February 2015, all paper gaskets on the valve covers were replaced with silicone gaskets. On 15 October 2015, cylinder number 3 was replaced due to low compression. On 10 June 2016, a pilot reported vibration in the right rudder control pedal; a visual inspection of the engine compartment and flight controls, along with a test of landing gear retraction and extension, revealed no issues.