Date:	Friday 10 December 2021
Time:	23:30
Type:	Swearingen SA-226AT Merlin IV
Owner/operator:	Castle Aviation
Registration:	N54GP
MSN:	AT-034
Year of manufacture:	1975
Total airframe hrs:	10633 hours
Engine model:	Honeywell TPE331-10UA-511G
Fatalities:	Fatalities: 1 / Occupants: 1
Aircraft damage:	Destroyed, written off
Category:	Accident
Location:	0,6 km SW of Manchester-Boston Regional Airport, NH (MHT) -   United States of America
Phase:	Approach
Nature:	Cargo
Departure airport:	Caldwell Wright Airport, NJ (CDW/KCDW)
Destination airport:	Manchester-Boston Regional Airport, NH (MHT/KMHT)
Investigating agency:	NTSB
Confidence Rating:	Accident investigation report completed and information captured

Narrative:
Castle Aviation flight CSJ921, a Swearingen SA-226AT Merlin IV, N54GP, was destroyed when it crashed into the bank of the Merimack River, about 600 m short of the threshold of runway 6 at Manchester-Boston Regional Airport, NH (MHT), New Hampshire, USA. The sole pilot onboard was fatally injured.
The airplane was on the ILS approach to runway 6 at Manchester Boston Regional Airport in darkness. During the approach, the pilot reported an engine failure at 23:30:42 but did not specify which engine. The aircraft crashed nine seconds later.
During that last 9-second period of the flight, the airplane’s groundspeed slowed from 99 kts to 88 kts, as it descended about 400 ft in a slight left turn to impact (the airplane’s minimum controllable airspeed was 92 kts). The slowing left turn, in conjunction with left wing low impact signatures observed at the accident site were consistent with a loss of control just prior to impact.

Probable Cause: The pilot's failure to secure and feather the left engine and increase power on the right engine after a perceived loss of engine power in the left engine, which resulted in a loss of control and impact with terrain just short of the runway. Contributing to the accident was a reduction in engine power from the left engine due to a 1st stage turbine blade midspan separation and material loss in the 2nd stage stator that were the result of engine operation at high temperatures for an extended period of time.

04:21 UTC / 23:21 local time:
SPECI KMHT 110421Z 00000KT 10SM BKN017 OVC075 M02/M05 A3016
time 0421Z, wind calm, visibility 10 statute miles, broken 1,700, overcast 7,500

wmur.com
Flightaware Flight track
ADSBexchange flight track

photo (c) Jacob Weaver; near Manchester-Boston Regional Airport, NH (MHT); 12 December 2021

Date/time	Contributor	Updates