EC-135 Hard Landing

[Flash]

When I saw this, I thought a Rivet Joint had a bad day.

Don't ruin my pedantic posting with pesky facts.

I had a similar thought, but not Rivet Joint as those are RC-135V/W's and all 12 1/2 versions of the Boeing EC-135 have long been retired.

EC-135 ALCC (Airborne Launch Control Center)


EC-135N ARIA (Advanced Range Instrumentation Aircraft) - Unfortunately involved in a crash of its own.



You can now go back to your regularly scheduled Eurocopter EC-135 thread.

 

[insanebikerboy]

I had a similar thought, but not Rivet Joint as those are RC-135V/W's and all 12 1/2 versions of the Boeing EC-135 have long been retired.

EC-135 ALCC (Airborne Launch Control Center)

View attachment 34355
EC-135N ARIA (Advanced Range Instrumentation Aircraft) - Unfortunately involved in a crash of its own.

View attachment 34356

You can now go back to your regularly scheduled Eurocopter EC-135 thread.

Don’t forget the Looking Glass mission. It did that for years.

 

[jmcquate]

I got a ride in an ARIA out of Write Pat during my brief stint in AF ROTC at UC (GO BEARCATS!).

 

[Flash]

Don’t forget the Looking Glass mission. It did that for years.

Give me a little credit.

I had a similar thought, but not Rivet Joint as those are RC-135V/W's and all 12 1/2 versions of the Boeing EC-135 have long been retired.

 

[Griz882]

I think there's some French influence here and there (like the Finnestron), but the single-biggest influence I've noticed is the AFM, which was written in German, converted to French, and then translated to English. I'm convinced that's why you "Vent" the engines instead of motor them. Crazy Frogs.

You sure they don’t mean the engines “vent” that way and ze rotors “vent” another?

 

[ChuckMK23]

Latest report from HAA EC-135 loss of control mishap/accident from a couple of years ago. Interesting reading! A acquaintance of mine who flies for my old program and is a well known FAA Helo DPE attributes the mishap/accident to pilot fatigue.

I'm sure @Gatordev has a take

Air Ambulance EC135 Loss of Control & Main Rotor / Engine Overspeeds - Aerossurance

An inflight upset, consistent with a SAS/AP CUT, resulted in a rotor overspeed, and reduction of power from both engines

aerossurance.com

 

[Gatordev]

well known FAA Helo DPE attributes the mishap/accident to pilot fatigue

So then what caused the bang? How does the aircraft all of a sudden go nose high and then pitch over?

I read the report the other day, but haven't had a chance to visit the docket to look at the mechanical report. I'm a little disappointed in the report because it seemed to completely ignore damage they said they found in the initial findings, specifically the damaged PCR. I thought that might be the smoking gun, but apparently not. It still would be interesting to know if the damage was done before or after the transient maneuver. Again, that may be in the other report I haven't seen yet.

But back to the fatigue comment... At cruise speed, when you lose the A/P and/or SAS, it's startling and it makes a bunch of noise ("GONG...GONG...") and the aircraft makes a pretty abrupt movement that even when you're sleepy, you're going to grab the controls in time to prevent an extreme nose high attitude like what they're reporting. I have a hard time buying fatigue being that much to not catch it in time. It seems the simulator testing backs that up.

The initial report also said the Medic reported rolling over because they were pinned to the ceiling. It's mentioned again in the final report, but after looking at the climb and descent data, I have a feeling they were just pinned by zero/negative G. I've had multiple, very experienced medical crew get disoriented as to what's happening (even something very benign) because they're sitting backwards.

As for the Np (oops, N1) overspeed...I don't remember being taught that the engine reverts to a manual mode, so that's good to know and learn. It would explain why there seemed to be nothing really wrong with the engines (externally) but he just kept descending straight to the ground (via auto).

Thanks for posting Chuck. I had the tab open in my browser but forgot to put this up yesterday.

 

[Random8145]

EC-135N ARIA (Advanced Range Instrumentation Aircraft) - Unfortunately involved in a crash of its own.

View attachment 34356

You can now go back to your regularly scheduled Eurocopter EC-135 thread.

That is one funny-looking plane.

 

[Gatordev]

Some additional, and I'd argue pretty relevant, info from the Airworthiness Report here...

On August 1, 2023, representatives from the NTSB, Air Methods, and Airbus
convened at FlightSafety International facilities in Denver, Colorado to study the
helicopter response to combinations of different cockpit configurations observed on
the accident helicopter. The baseline scenario used for all test cases was a 138 knot
cruise speed at a 1,400-foot altitude with an OAT of 25°F (-4°C) and calm air (no
winds). Furthermore, the altitude hold and heading hold autopilot upper modes were
active. The different configurations manipulated the following switches and circuit
breakers:

AIRWORTHINESS ERA22FA105
GROUP CHAIR'S FACTUAL REPORT PG 40 OF 42
- The AHRS knob on the RCU either in the “N” and “1” positions.
- The No. 1 inverter switch either in the “ON” and “OFF” positions.
- Overhead circuit breakers AHRS1 (on AC BUS I), ADC1, FCDM1, and Pitch
SAS extended.

With various combinations of cockpit configuration, and with hands off the cyclic
control, three scenarios were initiated: 1) pressing the “A.TRIM OFF” button on the
autopilot mode selector; 2) pressing the “AP OFF” button on the autopilot mode
selector; and 3) pressing the “SAS/AP CUT” button on the cyclic grip. 38 In all scenarios
except those involving the “SAS/AP CUT” button, the helicopter remained stabilized,
though the autopilot upper mode would decouple and both the master caution light
and the AP A.TRIM warning light would illuminate. In all scenarios when the “SAS/AP
CUT” button was pressed, the helicopter would become unstabilized and required
high pilot workload to regain control of the helicopter.
A dual FADEC failure was simulated, but due to limitations with the simulator, Nr
would not exceed 113%. In the scenarios that involved pressing the “A.TRIM OFF”
and “AP OFF” buttons on the autopilot mode selector, pilot workload was very high in
attempts to land the helicopter. In the dual FADEC failure scenario in which the
“SAS/AP CUT” button was pressed, pilot workload was extremely high and there was
a hard landing.

8.0 Past Relevant Occurrence
On November 28, 2011 at 1019 UTC, an EC135 P2+ helicopter, registration
YR-CPC, was involved in an inflight upset near Niculești commune in Romania. The
Romanian Civil Aviation Safety Investigation Commission (CIAS) investigated this
occurrence.39 The helicopter was not equipped with a FDR or a CVR.
According to the pilot of the occurrence, during cruise flight at an altitude of
3,000 feet and speed of 120 knots, the helicopter had a sudden and violent yaw to
the right, followed by a nose down dive with a right roll. The pilot recalled the altitude
hold and heading hold modes of the autopilot were active prior to the inflight upset,
he was flying with his hand on the cyclic control due to reported turbulence in the
area, and had no unusual cockpit indications prior to the inflight upset. During the
inflight upset, the pilot stated he disconnected the autopilot upper modes and
regained control of the flight after an altitude loss of about 1,500-2,000 feet. After the

pilot stabilized the helicopter, he noted the CAD displayed “YAW SAS” and
“ACTUATION”.
The investigation found that, due to the inflight upset, both engines
simultaneously had a Nf overspeed of 116-117% and overtorque of 127%.
Additionally, there was a NR overspeed in excess of 130% and a maximum mast
moment value of 103.3%. The investigation examined and found no functional
anomalies with the SEMAs, TRA, Fenestron control cable, and collective control
friction. Ultimately, the initiating cause for the inflight upset could not be determined.

I know they can't definitively prove what happened in the cockpit, but an AFCS release (AP CUT) of some kind seems to have similar results to the data being presented. It's interesting to see how quickly the transient maneuver can yield an over-speed. I've hit the SAS/AP CUT twice in flight when not training, once by accident when reaching for the AP disconnect while orbiting (barely noticeable other than the normal feeling of losing your SAS) and once intentionally at cruise when trying to clear a CAD Caution. As I mentioned in my previous post, at cruise the aircraft makes a startling move, but I was expecting that and had my hands on the cyclic. Since apparently there's examples of over-speeds in other situations, I could see how this might be a big factor, especially if your hands weren't on the cyclic and busy with something else like the iPad or fiddling with knobs in the cockpit.

And trying to fly AP and SAS off while also trying to deal with a dual-FADEC failure (both at low-side conditions) would definitely be a handful.

 

[ChuckMK23]

especially if your hands weren't on the cyclic and busy with something else like the iPad or fiddling with knobs in the cockpit.

Hence fatigue issue. (falling asleep?)

There is serious litigation on this accident. I suspect more will come out. This is interesting.

 

[Gatordev]

Hence fatigue issue. (falling asleep?)

Maybe, but it also states he just descended to clear the shelf. It sounded like he was in the middle of doing stuff in a terminal area versus droning on en route.

I'm still struggling to understand why you would have your FADECs fail to idle instead of some other power state. I guess because any other power state could still result in an over-speed (something the pilot corrects for when landing after a single FADEC malfunction) since there's no over-speed drain valve. I guess I just continue to be spoiled by how good the T700 design is, engine harnesses not-withstanding.