The airline transport pilot reported that the accident flight was the Cessna 441’s first flight after a phase maintenance check, and that he was repositioning the airplane to an airport about 40 nautical miles away.
While en route, the plane experienced a series of avionics and fuel-related anomalies.
He eventually declared an emergency and was cleared to land at the destination airport in Fargo, N.D.
The first approach for landing in instrument meteorological conditions resulted in a missed approach.
About this time, the airframe was accumulating ice and he cycled the deice boots.
During the second approach, the airplane broke out of the clouds, and he proceeded to land.
Before he initiated the landing flare, he reduced engine power to idle, fully extended the flaps, and flared the airplane. He stated the airplane was shaking and shuddering, but no stall warning horn sounded, and then the “bottom fell out.”
The airplane landed hard, and the left engine’s propeller blades struck the runway. The airplane incurred wing spar and propeller damage.
A post-flight examination of the airplane revealed between ½ to 1 inch of rime ice on the leading edge surfaces of both wings, the horizontal stabilizer, and the vertical stabilizer.
The pilot’s operating handbook stated that the deicing boots should be cycled as necessary when ice accumulation reached between ¼ and ½ inch. The amount of ice on the wing and empennage surfaces after the accident was consistent with the pilot not cycling the deice boots as prescribed, which resulted in an excessive ice accumulation on approach and a subsequent aerodynamic stall during the landing flare.
Probable cause: The pilot’s failure to cycle the surface deice boots during the instrument approach in icing conditions, which led to ice accumulation on the leading edges of the wings and empennage, and resulted in an aerodynamic stall and subsequent hard landing.
NTSB Identification: CEN16LA098
This January 2016 accident report is provided by the National Transportation Safety Board. Published as an educational tool, it is intended to help pilots learn from the misfortunes of others.
power to idle will also result in a high rate of descent…blades go flat to attempt to maintain an on speed condition resulting in increased drag
No single aviation text publishes these all in one place. That’s a crying shame in my view.
Stall behaviors –
1. Stall buffet, the wing-root separated flow strikes the empennage (shaking)
2. Wing tip drops uncommanded
3. Nose drop , uncommanded
4. Abrupt decay of control authority
5. Excessive sink rate for a given airspeed ( accelerated stall)
6. Stick on aft stop and no positive pitch rate.
Please note that a stall warning horn is not on that list.
He had a really bad day, and lived to walk away. Maybe he’ll think harder before taking a post-maintenance flight into IMC, regardless of the ‘capability’ of the machine. And for the airplane drivers….. is the stall-horn vane going to move if there is ice on the wing? We become complacent, after many hours of bad things Not Happening.
Teaching moment over.
This accident is somewhat similar the Cirrus SR-22T fatal accident GANews carried yesterday. Here the 441 pilot failed to use the de-ice boots and was lucky. The aircraft merely had “the bottom drop out” during the flare resulting in substantial damage, but no serious injury except to the pilot’s paycheck. The SR-22T pilot likewise failed to effectively use his anti-ice TKS during his approach to land (he turned it on for about 90 seconds then turned it off again shortly before entering an unrecoverable spin). Neither pilot was situationally aware… they both misjudged the ice load and were blase’ about the adverse impact it had on lift and controlability. Neither followed procedures mandated in their respective AFM for flight through icing conditions. We should be grateful to them for reaffirming our need to be familiar with our aircraft systems, and then follow recommended procedures.
” the airplane experienced a series of avionics and fuel-related anomalies. The pilot eventually declared an emergency and was cleared to land at the destination airport.”
Let’s see, autopilot malfunctions, fuel system anomalies (low pressure, x-feed pump failure) — very high workload in day IMC conditions, with odd noises, surging engine (reading the full report, I wonder how many CPLs would have lost it before getting to the runway).
At least this guy didn’t lose control of the plane and auger in.
NTSB failed to note all these major “distractions” that lead to declaring an in flight emergency. Had this been a two man crew with all of this, I wonder if the NTSB would have run a few simulations to see just how much workload they had with warnings not being given that they needed.
But they sure spent a lot of time on the de-icing boots and the POH.
Single pilot operations in Day IMC (thankfully not night), being unable to handle an ILS but going for a GPS approach (because of icing conditions?).
This guy was focused on keeping the plane flying — feeling a need to manually operate the de-icing boots. He was preparing to do a single engine approach because he thought the one engine was about to fail. He’d already done a missed approach and kept it under control.
I’d say this guy had his hands full and really could have used a student pilot in the right seat to just look out at the wings and maybe punch the deicing reset button or something.
You look at the 100Kt speed over the threshold… This guy knew he had problems, but he got it on the ground and walked away. Oh, and this was a first flight after maint — nothing said about the fuel system or A/P doing an uncommanded 180 turn.
Just think about that before saying this guy was blase’.
With all of those bad things happening, I wonder if the NTSB checked to see if the deicing booits were working. Seems to me that some or maybe most of the blame for this accident should have been assigned to the maintenance facility that did the phase maintenance check.