Accident to the Cessna 340 registered N38CM on 26/01/2022 at Saint-Denis-de-l'Hôtel

This is a courtesy translation by the BEA of the Final Report on the Safety Investigation (September 2022). As accurate as the translation may be, the original text in French is the work of reference.

Note: the following information is principally based on statements made by the pilot and the passengers. This information has not been independently validated by the BEA.

1. History of the flight

The owner, a pilot, accompanied by two other pilots, undertook an IFR ferry flight following a maintenance operation on the aircraft. They took off from Dinan-Trélivan aerodrome bound for Orléans airport where the aeroplane was based. After a discussion between the three pilots, the owner took the right seat and one of the two pilots took the left seat as pilot-in-command.

The sky was clear at take-off, during the climb and during the cruise at FL 160.

During the descent to Orleans, the pilot was cleared for the RNP23 approach. He indicated that the aeroplane entered a layer of cloud at an altitude of approximately 3,000 ft. He then noticed a layer of ice on the leading edges of the wings, similar in thickness to what he was used to encountering. He initiated a first de-icing cycle of the leading edges and the tail unit (see paragraph 2.2 Aeroplane Information).

In level flight at 2,100 ft, before intercepting the approach slope, the pilot checked the leading edges again and initiated a second de-icing cycle. He asked the owner to set the flaps to the first flap detent (flaps 15)[1], then extended the landing gear.

The pilot indicated that the autopilot intercepted the approach slope. The pilot extended the flaps to the next flap detent (flaps 30). The aeroplane exited the cloud layer at an altitude of about
800 ft. The pilot-in-command then checked the leading edges of the wings one last time, noted the presence of ice and initiated another de-icing cycle.

The final approach was made with flaps 30, at an indicated airspeed of approximately 115 kt[2]. The pilot-in-command and the pilot in the rear seat indicated that during the final approach the owner asked the pilot to reduce power several times, which the pilot refused saying that it was still too early.

On arriving overhead the runway, a few metres above the ground, the owner again asked the pilot-in-command to reduce power. The pilot-in-command lowered the power levers, the aeroplane sank instantly and hit the runway hard.

The pilot-in-command stopped the aeroplane on the runway centreline. The three occupants evacuated the aeroplane unharmed. The pilots found a thin layer of ice on the leading edges of the wings and a thicker layer on the leading edges of the horizontal stabilizer (see Figure 1). The propellers and the wings were damaged.

 Figure 1: ice on the horizontal stabilizer shortly after the event (source passenger)

2. Additional information

2.1. Meteorological information

The 16:30 Orléans - Saint-Denis-de-l'Hôtel airport METAR provided the following information:

• wind from 090° at 4 kt, varying between 040° and 120°;
• visibility 5,000 m;
• presence of fog;
• overcast at 400 ft;
• temperature -1 °C, dew point -1 °C;
• QNH 1035 hPa.

2.2. Aeroplane information

The Cessna 340 is equipped with the following ice protection systems:

• a pneumatic de-icing system for the leading edges of the wings, horizontal stabilizer and fin;
• an electrical anti-icing system for the propellers;
• an electrical heating system for the pitot heads, AOA sensor, stall indicator, static pressure probes and the windscreen.

According to the aeroplane flight manual, the de-icing system of the wing and tail unit leading edges is designed to remove the ice after a period of accumulation. It consists of boots that are inflated by air taken from the engines. An inflation and deflation cycle lasts about 45s.

The flight manual requires the pilot to activate the system in icing conditions when the thickness of the ice reaches between ¼ and ½ inch[3], and to repeat the cycles as many times as necessary, leaving at least 45 s between each cycle.

The flight manual states that approaches on all engines operating are conducted at an approach speed of 94 kt with flaps extended to 45°. In icing conditions, the flight manual requires the pilot to  increase the approach speed to compensate for the earlier onset of  buffeting - indicating an imminent stall - due to the presence of  ice on the unprotected areas. The value of the speed increase is not specified in the manual. Neither does the manual provide approach speeds for other flap configurations.

2.3. Pilot information

The 57-year-old pilot held a CPL(A) licence with MEP and IR ratings. He had logged approximately 10,000 flight hours, including around 2,500 h on the BE 90, 2,000 h on the BAE Jetstream 32, and 650 h on the BE 350, which has similar wing de-icing systems to the Cessna 340. He also had
1,500 flight hours on the Raytheon Premier. He had logged 3 flight hours on the Cessna 340.

The pilot indicated that he had good experience with icing conditions on aeroplanes equipped with leading edge pneumatic de-icing systems. He indicated that on final he asked the owner to select full flaps, and according to him, the owner replied that it was not necessary. The pilot indicated that he “took note” of the owner's response and “reluctantly” continued the approach with flaps 30.

This was the second flight he had flown with the owner. He indicated that the owner was "an excellent pilot", a champion aerobatic pilot, who was used to carrying out his approaches with flaps 15, at an indicated airspeed of 95 kt[4].

2.4. Owner’s statement

The owner held a PPL(A) licence and IR/SE, IR/ME and aerobatic CRI ratings. He had logged approximately 1,700 flight hours, of which approximately 800 h on aerobatic aeroplanes and 250 h on the N38CM. He also held several aerobatic titles.

The owner did not recall any discussion about full flap extension and indicated that he does not interfere with the management of the flight when he is a passenger unless asked to do so by the pilot. He indicated that he told the pilot to reduce power on arriving overhead the runway in preparation for landing.

2.5. Statement of pilot in rear seat

He stated that the aeroplane instantly went from "flight" to "stall", without any prior vibration or other warning signs, at a speed approximately 40 kt above the stall speed in this configuration. He also added that during previous stall tests conducted on this aeroplane, in non-icing conditions, vibrations occurred as the aeroplane approached stall. According to the three occupants, it was probably the horizontal stabilizer that stalled when the power was reduced.

He added that on the outbound flight from Orléans at around 12:50 on the same day, the aeroplane they used, a Bonanza without a wing de-icing system, was not contaminated by ice. He was surprised that on the return trip, at about 16:00, the conditions were so different and colder.

He and the pilot intended to rent the aeroplane from the owner later on. In his opinion, the owner's presence in the right seat and his status as an aerobatic champion may have prompted the pilot to reduce the power requested by the owner.