N3618WPiper PA-32-260 · 1966

On April 16, 2022, about 1952 eastern daylight time, a Piper PA-32-260, N3618W, was substantially damaged when it was involved in an accident near Grantsville, Maryland. The pilot and two passengers received minor injuries. The airplane was operated as a Title 14 Code of Federal Regulations Part 91 personal flight.

According to the pilot, he performed a preflight inspection with no anomalies noted, received a weather briefing, and departed Wabash Municipal Airport (IWH), Wabash, Indiana, destined for Martin State Airport (MTN) in Baltimore, Maryland, on an instrument flight rules clearance. About 2 hours into the flight, the airplane was about 11,000 ft mean sea level (msl) approaching clouds, and the pilot increased engine power and turned the pitot heat on. The airplane was “underperforming and unable to climb over the clouds.” After entering the clouds, he noticed the airspeed decreasing and the autopilot increasing the pitch of the airplane to maintain altitude. The pilot disengaged the autopilot, decreased the pitch attitude of the airplane, and noted that it was “difficult to maintain pitch control.” He examined the wings and windscreen for any signs of ice but saw none.

The pilot notified air traffic control of his difficulty controlling the airplane, and they declared an emergency for him. The airplane descended out of the clouds into heavy rain. The pilot elected to perform a forced landing to a road. During the landing the airplane impacted trees and terrain, resulting in substantial damage to the fuselage, wings, and empennage.

Postaccident examination of the airframe confirmed flight control continuity from the cockpit flight controls to the flight control surfaces through multiple cuts made by recovery personnel and tensile overload fractures. Engine crankshaft and valvetrain continuity were confirmed when the propeller was rotated by hand, and compression was observed on all cylinders. The cylinders were examined with a lighted borescope, and no anomalies were noted. There was no evidence found of pre-impact anomalies that would have precluded normal operation.

According to the Airplane Flight Manual and an engineering drawing, the airplane was required to have a placard on the left side of the cockpit that states, “THIS AIRCRAFT APPROVED FOR NIGHT IFR NON-ICING FLIGHT WHEN EQUIPPED IN ACCORDANCE WITH FAR 91 OR FAR 135.” The placard was not located in the cockpit after the accident.

Composite weather images for radar scans initiated at 1935:50, 1940:09, 1944:28, and 1948:46, respectively, indicated light to moderate precipitation along the airplane’s flight path (figure 1). The upper air sounding indicated that the freezing level was located at 5,100 ft msl, and cloud conditions were expected up to 13,000 ft msl.

Figure 1 - Weather radar image for scan initiated at 1948:46 with the weather encounter location marked with a red circle. The flight track is depicted as a magenta line with black arrows pointing in the direction of travel.

The National Weather Service’s Current Icing Product (CIP) and Forecast Icing Product (FIP) are intended to supplement AIRMETs and SIGMETs. The FIPs for 9,000 ft msl, 10,000 ft msl, and 11,000 ft msl indicated a 40 to 85% probability of icing from 9,000 ft msl to 11,000 ft msl over the area corresponding to the weather encounter. The FIPs indicated that the icing intensity would range from “light” to “heavy.”

An AIRMET for icing conditions valid from 1700 through 2000 indicated moderate icing between the freezing level and 17,000 ft msl.

A performance study was conducted using automatic dependent surveillance-broadcast (ADS-B) data to determine specific airplane performance characteristics. The study showed that during level flight above 10,000 ft msl, there were increases in drag that were also present during the final descent of the airplane. The study indicated that, at 1945, the pitch was increasing and the airspeed was decreasing, which was consistent with the pilot’s report that the autopilot was increasing the pitch to maintain altitude. Just after 1946:30, the pitch decreased, corresponding to when the pilot disconnected the autopilot and decreased the pitch attitude. The airplane began to descend 15 seconds later, and there was a marked increase in drag.

At 1947, the airplane began a turn to the right; pitch again increased; but the descent continued while lift and drag increased. At that time, drag was four times higher than any other time in the flight. The airplane’s calculated airspeed slowed to near 54 knots, which was below the power off, gross weight, no flaps stall speed of 57 knots. At 1948, the angle of attack, pitch, lift, and drag all decreased suddenly; this loss of lift was consistent with an aerodynamic stall. The airplane then recovered and gained airspeed while continuing to descend.

At 1951, the drag quickly increased but without an increase in lift, and the airplane began a turn to the right. At 1951:30, the lift dropped sharply without having increased during the increase in drag. This sudden loss of lift occurred at a much lower lift coefficient and angle of attack than the previous event at 1948 and at an airspeed above 100 knots, well above the airplane’s stall speed. The airplane recovered briefly before the drag began to increase again. The airplane was still slowing when the ADS-B data ended as the airplane descended below 150 ft above the terrain. The accident site was located about 2,500 ft beyond the last data point.

Generally, ice accumulation on an airplane’s wings increases drag and reduces the amount of lift the wing can produce. Ice accumulation on the fuselage of an airplane also increases drag. Additionally, ice accumulation on propeller blades reduces the amount of thrust that can be produced.

The pilot did not request weather information from Leidos Flight Service; however, he did request and receive a ForeFlight weather briefing at 1713 with a proposed departure time of 1725. The pilot reported that there was moderate icing forecast for the time of the flight.