NT Air King Air Accident - Pilot Discussion Thread

[J31]

According to the TSB the aircraft was configured with flight idle selected on the left engine, gear down and the flaps at 60%. In that configuration the speed will decay very fast and you WILL lose control by increasing power on only the right engine. At low altitude the only way out is to increase power up on BOTH engines.

At flight idle the prop produces a lot of drag. To get ZERO drag with the engine running you must carry about 400 fp of torque or feather the prop.

As I recall the Beech abnormal checklist is not very detailed, leaving the "low power" interpretation up to the crew. In addition with the engine still running it is vague as to using the single engine landing checklist which recommends maximum of 30% flap.

The approach should have been flown with the left engine at above 400 fp of torque or feathered and the flaps at 30 %.

[pelmet]

As I recall the Beech abnormal checklist is not very detailed, leaving the "low power" interpretation up to the crew. In addition with the engine still running it is vague as to using the single engine landing checklist which recommends maximum of 30% flap.

The approach should have been flown with the left engine at above 400 fp of torque or feathered and the flaps at 30 %.

My old A100 manual has a single Engine Landing Checklist that says...

Use normal landing procedures with the following exceptions:
1. Propeller rpm(operative engine) - Full increase
2. Approach Speed - 10 knots above normal

[oldtimer]

I do not want to comment on the actions of the crew because I did not know them and I was not in their shoes but I do have some comments about mods done to aircraft because I can speak from real experience and pilots may learn from these comments.
The PT6 manual says to reduce power when the engine oil pressure drops below 90 psi but stays above 40 psi. Reduced power means below 1000 ft/lbs torque, I think. Oil pressure below 40 psi the manual RECOMMENDS the engine be shut down. The oil pressure gauges on GXRX were AC powered and there was no low oil pressure annunciator when I flew the airplane, long before NT Air aquired the airplane. I also flew a sister ship (11 serial numbers prior) both before the Raisbec mod and after it was modified. The Raisebec mods do great things to the peformance and stability of the airplane. But the 4 blade propellers can creat a problem. When flight idle with the power levers is selected, drag is considerable and pilots are reluctant to bring the power levers to flight idle on landing because the airplane will plop down on the runway which is a valuable aid when landing on a short runway in gustey winds. The propellers must remain above 1000 RPM to preclude a harmonic vibration common to 4 bladed props. Beech 350 has the same caution. It has been my experience that the increase in drag at idle is a common feature as the number of propeller blades is incrased. I discoverd this first with a Norseman (3 blade prop changed to a 2 blade), then a Cessna 310, a Cessna 206 (A 2 blade prop changed to a 3 blade) and the Beech 100 Raisbec and the Beech B200 (3 blade prop changed to a 4 blade). Now if the pilot allows the airspeed to decrease to a low value, the airplane may not have enough performance to recover. This can lead to a problem because the low airspeed also comes with a higher than normal sink rate and if the crew are not quick enough to recognise the events, they run out of altitude, airspeed and ideas and that is not a comfortable spot to be in. If the engine was running and supplying oil pressure, the propeller would remain on speed but if the engine failed to supply oil pressure to the prop governor, the prop should go to feather. But if the engine failed on approach, the propeller would begin to fine off to attempt to maintain RPM as long as the prop governor had (residual) oil which would not only create drag but also blocks airflow over a large portion of the wing. Airspeed, altitude and ideas all gone. I do believe the same factors affected the Borek King Air 100 at Kirby Lake. Simply stalled the airplane on approach. That is my opinion and I am open to comments or corrections.

[pelmet]

Yes, it is very very easy to close both latches and have the crow's feet below, and not on, the cross pins of the cowl. The cowl will be closed, the latches will be closed, but nothing is being held down. It's just sitting there. The captain does a "cowl push", x2, on the "hail marry".
While engaging the latches, you must see the crows feet engage the cross pin on the cowl before closing the latch...x2

2016-03-18

An Air Georgian Beech 1900D (C-GAAR), operating as flight GGN7260, departed Toronto LBPIA
(CYYZ) en route to Kingston (CYGK). At 13000 feet the flight crew heard a loud noise. A visual
inspection revealed that the right engine upper forward cowling had departed the aircraft. There
were no handling difficulties and flight crew elected to return to Toronto. An emergency was not
declared and the aircraft landed without further incident.

Subsequently, an inspection showed that the engine cowling had dented the right side of the
fuselage. As well, the cowling struck the right stabilon causing significant damage; a piece of the
cowling remained imbedded in the stabilon. The aircraft is grounded while maintenance repairs the
dented fuselage and replaces the stabilon.

Maintenance had been accomplished on the engine a week prior to the occurrence. The cowling
had been secured in accordance with the maintenance manual and lock-wired closed as per
company procedures. A preliminary company investigation indicates that 3 of the 4 cowling cam
latch devices may not have been engaging properly. An Air Georgian fleet wide campaign has
been undertaken to inspect all cam latches for proper fastening as part of an ongoing internal
company investigation.

[rigpiggy]

Wrt the 4blade conversion aren't the flight idle stops set higher to counter this?

[oldtimer]

I seem to recall that the flight idle stops were indeed reset to compensate for the increased drag and the machines I flew were within specs. I also found the drag higher. Not that much but at slow speeds, it was different and it took me a while to become familiar with the airplane. I agree with many that the mod did good things to the airplane except for this one small feature.

[GyvAir]

Yes, it is very very easy to close both latches and have the crow's feet below, and not on, the cross pins of the cowl. The cowl will be closed, the latches will be closed, but nothing is being held down. It's just sitting there. The captain does a "cowl push", x2, on the "hail marry".
While engaging the latches, you must see the crows feet engage the cross pin on the cowl before closing the latch...x2

2016-03-18

An Air Georgian Beech 1900D (C-GAAR), operating as flight GGN7260, departed Toronto LBPIA
(CYYZ) en route to Kingston (CYGK). At 13000 feet ........

For those not familiar, spaners post was referring to the aft cowl (shown open in the photo below) which latch on the right and hinge on the left. The Georgian incident involved the forward cowling which requires a wrench to engage four cam hook and pin assemblies, two on each side; common to pretty much all of the Beech turboprops. The 1900 has a mess of camlocked panels instead of the hinging aft cowling.

pelmet: I'll copy your post over to the thread related to the 1900 incident for those that were following it.

[av8ts]

http://www.cbc.ca/beta/news/canada/brit ... -1.3999375

[pelmet]

"Supreme Court justice rules granting access to the recorder serves a public good"

Well, maybe it is time that it was made as a public record the way the Americans do.