FAA Accident and Incident Notification(s): Notice(s) Created 24-JUN-22

[GFields]

Does anyone know more about this story?

A HELICOPTER STRUCK A DRONE AT 1500 FEET NEAR THE INTERSECTION OF DOBBINS ROAD AND ROUTE 601 IN BOONVILLE, NC. THE AIRCRAFT RETURNED TO ZEF AND REPORTED DAMAGE TO A ROTOR.

The information doesn't say if the 1500 fee is MSL or AGL

IDENTIFICATION
Date:	23-JUN-22
Time:	14:59:00Z
Regis#:	N2158T
Aircraft Make:	SCHWEIZER
Aircraft Model:	269C
Event Type:	ACCIDENT
Highest Injury:	NONE
Aircraft Missing:	No
Damage:	SUBSTANTIAL
LOCATION
City:	ELKIN
State:	NORTH CAROLINA
Country:	UNITED STATES
DESCRIPTION
Description:	HELICOPTER STRUCK A DRONE AT 1500 FEET NEAR THE INTERSECTION OF DOBBINS ROAD AND ROUTE 601 IN BOONVILLE, NC. AIRCRAFT RETURNED TO ZEF AND REPORTED DAMAGE TO A ROTOR.

 

[Rich QR]

The information doesn't say if the 1500 fee is MSL or AGL

I just looked up the altitude of Boonville, NC, and google says it's at 1,099 ft. So 1500' MSL would be about 400' AGL. I have no idea how level the terrain is, or whether the accident site terrain is above or below the reference spot that was used to determine that 1,099 altitude, so take that approximation with a grain of salt.

My wild and unfounded guess is that the altitude in the report was being measured MSL, not AGL, since sea level is the standard used by altimeters in crewed airplanes, as well as by ATC (at least until they get into the flight levels).

 

[Ty Pilot]

I agree

BoonVille NC's elevation is 1,099 feet above MSL so accident report is showing MSL.

This Article says the collision happened around 500 AGL.

So it looks like you had a drone at 400AGL in an area that had an 1,100 elevation thus the 1500 in the report is likely MSL.

 

[BigAl07]

I'm aware of his incident but it's currently an ACTIVE investigation so that's all that can be reported at the moment.

Thank goodness the H269 was able to land safely without any further incident. It's important to note (for all of us) that the level of damage is noted as "substantial".

 

[Yorkshire_Pud]

Just out interest is there any impact damage to a chopper's rotor (I assume that means a rotor blade) that wouldn't necessitate a blade replacement?
I am not trying to make light of the incident, it's just that to my mind any impact damage would be regarded as critical.

 

[Rich QR]

Just out interest is there any impact damage to a chopper's rotor (I assume that means a rotor blade) that wouldn't necessitate a blade replacement?
I am not trying to make light of the incident, it's just that to my mind any impact damage would be regarded as critical.

Search the web for terms like "helicopter rotor damage repair" and you'll find descriptions of repair facilities. There definitely is such a thing as repairable damage, and of course there are possible problems that would require outright replacement.

Of course I am not drawing any conclusions whatsoever about this specific incident.

 

[GFields]

Just out interest is there any impact damage to a chopper's rotor (I assume that means a rotor blade) that wouldn't necessitate a blade replacement?
I am not trying to make light of the incident, it's just that to my mind any impact damage would be regarded as critical.

The report list damage as Substantial.

 

[Yorkshire_Pud]

The report list damage as Substantial.

yes I know, it also says "AIRCRAFT RETURNED TO ZEF AND REPORTED DAMAGE TO A ROTOR." hence my question.

 

[BigAl07]

Just out interest is there any impact damage to a chopper's rotor (I assume that means a rotor blade) that wouldn't necessitate a blade replacement?
I am not trying to make light of the incident, it's just that to my mind any impact damage would be regarded as critical.

Of course there is. If it's only superficial, as in it can be buffed out, but that depends on the composition of the blade. Even a slight scratch in a composite blade could deem it Replacement Only.

I would be willing to be that "substantial damage" will mandate a teardown and inspection of the blade and probably the hub assembly if not also the main shaft assembly as well. Substantial Damage would likely mean that at least one of the blades will be replaced and depending on the specifications possibly all blades to be replaced. Rotor Blades have a "finite" life and need to be replaced at certain predefined intervals even without any UAS damage. This could be just hours of use but in some instances (composite designed) also have a Calendar Life separate from hours of use.

Keep in mind that any deformation will change the blade's physics in terms of lift & drag and that's not even taking into account the potential blade failure if the component is structurally compromised and spinning around with some crazy centrifugal forces. On smaller manned helicopters the force at the blade root could be 6 - 12 TONS on each blade. Larger non-military helicopters could go over 40 TONS of force at blade root.

 

[BigAl07]

That alt reported is indeed MSL which, as noted above would be 400' AGL yet the email report I received had it listed at 500'AGL which could have been a typo or an overly zealous estimation . . . .

 

[Yorkshire_Pud]

I must admit I am quite surprised that it is permissible to buff out minor damage, I'd have thought that crack propagation from nicks and or cracks was a major concern given the 'centrifugal forces' and cyclic loadings they are subjected to.
My indirect point being that I was wondering if impact of the drone with a rotor blade alone might qualify as substantial damage. But I suppose that it is possible that the drone could have caused substantial damage to the helicopter's body and then either the drone or debris hit the rotor.

 

[Richard R]

I'm more concerned about the story here. Just another irresponsible drone pilot creating a sensational story that will, with other similar events, have consequences for us all.

 

[BigAl07]

I must admit I an quite surprised that it is permissible to buff out minor damage, I'd have thought that crack propagation from nicks and or cracks was a major concern given the 'centrifugal forces' and cyclic loadings they are subjected to.
My indirect point being that I was wondering if impact of the drone with a rotor blade alone might qualify as substantial damage. But I suppose that it is possible that the drone could have caused substantial damage to the helicopter's body and then either the drone or debris hit the rotor.

The details are very limited right now but everything I have available only indicate rotor blade impact. It may be several months before a more detailed report is released for public consumption.

 

[Rich QR]

That alt reported is indeed MSL which, as noted above would be 400' AGL yet the email report I received had it listed at 500'AGL which could have been a typo or an overly zealous estimation . . . .

Or it could have been the terrain. Here's part of the USGS topo map around Boonville, NC. I drew a crude red arrow pointing at the intersection in the report. The 20' contour lines are pretty close to each other in that area. That intersection happens to have a 937' benchmark very near it, but when the report says "near the intersection", I assume they mean "closer to the intersection than to any other significant landmark". There are some hills above 1100' and some valleys below 900' that would fit that description.

Plus, it could be that the 1500' reported altitude is off by a few tens of feet, maybe significantly more.

 

[BigAl07]

Or it could have been the terrain. Here's part of the USGS topo map around Boonville, NC. I drew a crude red arrow pointing at the intersection in the report. The 20' contour lines are pretty close to each other in that area. That intersection happens to have a 937' benchmark very near it, but when the report says "near the intersection", I assume they mean "closer to the intersection than to any other significant landmark". There are some hills above 1100' and some valleys below 900' that would fit that description.

Plus, it could be that the 1500' reported altitude is off by a few tens of feet, maybe significantly more.
View attachment 150873

Rich I fully see your point but . . . .
I'm going from the information given to me during a conversation with an FAA Safety Team Manager in that district. While he could be mistaken on that one I'm going to go with his specific words until proven wrong

 

[db4476]

Here's my first thought. Could the drone pilot not hear the helicopter? Where I'm at, helicopters are frequently flying nearby, and I can hear a copter long before it comes into view from beyond the hills.

Cheers!

 

[Ty Pilot]

Here's my first thought. Could the drone pilot not hear the helicopter? Where I'm at, helicopters are frequently flying nearby, and I can hear a copter long before it comes into view from beyond the hills.

Cheers!

It has been shown/discussed on this forum that being able to hear an oncoming aircraft is not always a given. Many factors such as wind, ambient sounds, machinery and things like busy roadways can mask or dampen the sounds an oncoming aircraft makes. Also if the drone pilot was task-saturated or busy focusing on what he was trying to achieve - he may have been able to hear it, but did not have the situational awareness to react.

But all of this is merely speculation until the investigation is over and the facts are known.

 

[Blairsville]

I live in the Blairsville, GA area. Mostly during the summer months, military aircraft, helicopters, fighter jets, C-17’s run these valleys at treetop level. My home is 1983’ above sea level but several times, the aircraft are low enough to read the serial numbers along the fuselage. Apparently, Camp Frank Merrill near Dahlonega Ga is having Ranger training.

 

[GregS]

I just looked up the altitude of Boonville, NC, and google says it's at 1,099 ft. So 1500' MSL would be about 400' AGL. I have no idea how level the terrain is, or whether the accident site terrain is above or below the reference spot that was used to determine that 1,099 altitude, so take that approximation with a grain of salt.

My wild and unfounded guess is that the altitude in the report was being measured MSL, not AGL, since sea level is the standard used by altimeters in crewed airplanes, as well as by ATC (at least until they get into the flight levels).

I just did a search and it said Boonville, NC was 988'. This came from Boonville's site.
Wonder which is correct?

 

[thispilothere]

Is the drone pilot known? How far out was the drone?