We have had a T/R belt failure just after coming in to land in the hover 2 up confined area, total destruction of the RW.
Just wondering if the Vee belt could be upgraded as there has been a lot of improvements in belt technology.
this came up in a google search as maybe a better belt for our application.optibelt SUPER XE-POWER PROHigh performance wedge belts - raw edge, moulded cogged

(02-08-2026, 10:05 PM)Graeme Smith Wrote: We have had a T/R belt failure just after coming in to land in the hover 2 up confined area, total destruction of the RW.
Just wondering if the Vee belt could be upgraded as there has been a lot of improvements in belt technology.
this came up in a google search as maybe a better belt for our application.optibelt SUPER XE-POWER PROHigh performance wedge belts - raw edge, moulded cogged

Oh no! im very glad you are still ok. another point for the survivability and crash worthiness of the frame. 
In what manor was the tail rotor loss of thrust developed? sudden belt breakage? slower developed like belt slipping? 

my biggest concern with the belts have always been oil/coolant contamination affecting belt drive friction... i've heard a few instances of coolant from the overflow reservoir leaking onto the tail belts. same with pinhole leaks on the engine manifolds. 

i hope you're able to find more details, i am very sorry for the loss of your ship. was this the one you've shared pictures of previously with alot of your upgrades?

Yes it was REL, the Red RW, I had sold it to a local friend and he was meticulous re belt tension etc, It appears that one of the belts broke, we are still waiting for our CASA to attend and inspect. He had a non eventful flight 2 up and had finalised his approach to his landing area and as it came back into the hover he applied right pedal then it began to turn as he then applied all right pedal but it did not stop approx 6 rotations then he lowered collective to touch the ground and one skid grabbed and spun and then it rolled over, but the occupants were ok the harness kept them secure, they exited through the broken screen and managed to clear the damage then they saw petrol leaking out so that was dealt with that everyone was unhurt but the RW is a complete right off with maybe a few parts still OK.

in a perfect world i suppose we would find a Kevlar/aramid reinforced cogged 3VXK1120 and 3VXK1180 belt to fit our needs.

it makes sense why it would be a sudden failure coming into a hover after getting warmed up after a flight and finally letting loose at a high power/torque setting with lots of pedal needed. :/

i love the idea of a cogged belt for additional cooling/less stress on the belt around the pulleys, easier power transmission, however i think the real culprit is the bands weakening. i dont know what the original bands are EPDM, poly, or aramid?

my belts are getting replaced due to their age, i understand these are a 3 year item? i have new mitsuboshi red label main belts on the way for the same reason and i havnt ordered tail drive belts yet, so i am interested in what we can find!!

i just wonder if there is a kevlar reinforced/not wrapped, cogged belt out there.

(02-09-2026, 09:49 AM)Lyle Swallows Wrote: in a perfect world i suppose we would find a Kevlar/aramid reinforced cogged 3VXK1120 and 3VXK1180 belt to fit our needs.

it makes sense why it would be a sudden failure coming into a hover after getting warmed up after a flight and finally letting loose at a high power/torque setting with lots of pedal needed. :/

i love the idea of a cogged belt for additional cooling/less stress on the belt around the pulleys, easier power transmission, however i think the real culprit is the bands weakening. i dont know what the original bands are EPDM, poly, or aramid?

my belts are getting replaced due to their age, i understand these are a 3 year item? i have new mitsuboshi red label main belts on the way for the same reason and i havnt ordered tail drive belts yet, so i am interested in what we can find!!

i just wonder if there is a kevlar reinforced/not wrapped, cogged belt out there.

---

I am following up with Optibelt here in Australia, will advice what I find out.

Wow, glad to hear everyone is okay and thank you very much for sharing it with use Graeme! Yes, it's been proven time and time again that it is a very crashworthy airframe in terms of survivability. We just need to find ways to reduce mechanical failures even further, so I'm on board with identifying a suitable tail rotor belt replacement.

I have a few questions:

1. How old was the belt that failed?
2. Was the helicopter stored indoors away from elements and UV light?
3. How many hours (TT) on the helicopter?
4. What brand of belts were installed?
5. Are there temperature indicators installed on the pulleys? If so, was the highest indicated temperature reached?

I'd like to start tracking this kind of data whenever I can. I'll try to scrub information on accidents over time to see if we can create some useful statistics and charts with machine learning/AI tools (I will post them here). However, we'd need enough data for it to work reliably, this could take many years to gather. So if anyone is reading this that knows details of an accident, feel free to create a thread in this forum, even if it occurred many years ago!

(02-09-2026, 08:45 PM)Jared Hartzell Wrote: Wow, glad to hear everyone is okay and thank you very much for sharing it with use Graeme! Yes, it's been proven time and time again that it is a very crashworthy airframe in terms of survivability. We just need to find ways to reduce mechanical failures even further, so I'm on board with identifying a suitable tail rotor belt replacement.

I have a few questions:

1. How old was the belt that failed? from the time I received them approx 2.5 yerars
2. Was the helicopter stored indoors away from elements and UV light? Yes always stored in my shed
3. How many hours (TT) on the helicopter? about 65
4. What brand of belts were installed? The belts were supplied by Robin
5. Are there temperature indicators installed on the pulleys? If so, was the highest indicated temperature reached? Don't know yet as the wreck is being held till it can be formally examined by CASA

I'd like to start tracking this kind of data whenever I can. I'll try to scrub information on accidents over time to see if we can create some useful statistics and charts with machine learning/AI tools (I will post them here). However, we'd need enough data for it to work reliably, this could take many years to gather. So if anyone is reading this that knows details of an accident, feel free to create a thread in this forum, even if it occurred many years ago!

(02-09-2026, 09:01 PM)Graeme Smith Wrote:

(02-09-2026, 08:45 PM)Jared Hartzell Wrote: Wow, glad to hear everyone is okay and thank you very much for sharing it with use Graeme! Yes, it's been proven time and time again that it is a very crashworthy airframe in terms of survivability. We just need to find ways to reduce mechanical failures even further, so I'm on board with identifying a suitable tail rotor belt replacement.

I have a few questions:

1. How old was the belt that failed? from the time I received them approx 2.5 yerars
2. Was the helicopter stored indoors away from elements and UV light? Yes always stored in my shed
3. How many hours (TT) on the helicopter? about 65
4. What brand of belts were installed? The belts were supplied by Robin
5. Are there temperature indicators installed on the pulleys? If so, was the highest indicated temperature reached? Don't know yet as the wreck is being held till it can be formally examined by CASA

I'd like to start tracking this kind of data whenever I can. I'll try to scrub information on accidents over time to see if we can create some useful statistics and charts with machine learning/AI tools (I will post them here). However, we'd need enough data for it to work reliably, this could take many years to gather. So if anyone is reading this that knows details of an accident, feel free to create a thread in this forum, even if it occurred many years ago!

Thank you for the prompt response. Let us know what CASA finds!

I spoke with the Optibelt suppliers here in Australia and they checked out the current belt Robin supplied against the #vXK1120 & 1180 and they said both belts are not approved to run twisted (our system twists the belts 30 degrees between each set of pullies. So I then asked Google what is the best belt that would handle the twist and the power etc, this is the responce.......

Based on the need for a 3VX-section cogged belt (approx. 1180mm effective length) capable of handling a 30-degree twist, the best alternatives to the Optibelt 3VX1180 XEP (Super XE-POWER PRO) are those that emphasize high flexibility, EPDM rubber construction, and raw-edge design to reduce bending stress and manage misalignment. 
The best alternatives for high-twist, raw-edge applications include:
Top Alternatives to Optibelt 3VX1180 XEP

1. Gates Quad-Power 4 (XPZ/3VX):
   • Why: This is a premium EPDM rubber, raw-edge, cogged, maintenance-free belt that rivals the Optibelt XEP. It is designed for high efficiency and flexibility, allowing it to handle twisting and back-side idlers better than standard wrapped belts.
     
2. BESTORQ 3VX1180 Raw Edge/Cogged:
   • Why: These are highly engineered for flexibility, with manufacturers claiming they require 40% less energy to bend around pulleys compared to standard belts. This flexibility is ideal for handling 30-degree twists without excessive heat buildup.
     
3. Optibelt SUPER X-POWER M=S (3VX1180):
   • Why: If staying with Optibelt, the slightly lower-tier (but still very high performance) Super X-Power is an excellent, flexible, raw-edge cogged option.
     
4. PIX-X'set (3VX1180):
   • Why: A high-performance molded cogged belt with good flexibility and power capacity, often used as a direct, high-quality replacement for 3VX raw-edge belts. 
     

Key Considerations for 30-Degree Twists

• Raw-Edge Cogged Design: Only use "raw edge cogged" (molded cogged) belts. These have no fabric covering on the sides, which allows for much greater flexibility and reduced stress when subjected to a 30-degree twist.
  
• Material: EPDM rubber is preferred as it better handles the heat generated by the increased stress of a twisted drive compared to traditional neoprene.
  
• Banded vs. Single: Ensure you are using a single belt (or a, accurately matched set) for high-twist applications; banded belts (multiple belts joined together) are not designed for twists. 
  

Conclusion: The Gates Quad-Power 4 (3VX1180/XPZ1180) is likely the best direct alternative for maximum flexibility in a 30-degree twist scenario.

(02-10-2026, 07:15 AM)Graeme Smith Wrote: I spoke with the Optibelt suppliers here in Australia and they checked out the current belt Robin supplied against the #vXK1120 & 1180 and they said both belts are not approved to run twisted (our system twists the belts 30 degrees between each set of pullies. So I then asked Google what is the best belt that would handle the twist and the power etc, this is the responce.......

Based on the need for a 3VX-section cogged belt (approx. 1180mm effective length) capable of handling a 30-degree twist, the best alternatives to the Optibelt 3VX1180 XEP (Super XE-POWER PRO) are those that emphasize high flexibility, EPDM rubber construction, and raw-edge design to reduce bending stress and manage misalignment. 
The best alternatives for high-twist, raw-edge applications include:
Top Alternatives to Optibelt 3VX1180 XEP

1. Gates Quad-Power 4 (XPZ/3VX):
   • Why: This is a premium EPDM rubber, raw-edge, cogged, maintenance-free belt that rivals the Optibelt XEP. It is designed for high efficiency and flexibility, allowing it to handle twisting and back-side idlers better than standard wrapped belts.
     
2. BESTORQ 3VX1180 Raw Edge/Cogged:
   • Why: These are highly engineered for flexibility, with manufacturers claiming they require 40% less energy to bend around pulleys compared to standard belts. This flexibility is ideal for handling 30-degree twists without excessive heat buildup.
     
3. Optibelt SUPER X-POWER M=S (3VX1180):
   • Why: If staying with Optibelt, the slightly lower-tier (but still very high performance) Super X-Power is an excellent, flexible, raw-edge cogged option.
     
4. PIX-X'set (3VX1180):
   • Why: A high-performance molded cogged belt with good flexibility and power capacity, often used as a direct, high-quality replacement for 3VX raw-edge belts. 
     

Key Considerations for 30-Degree Twists

• Raw-Edge Cogged Design: Only use "raw edge cogged" (molded cogged) belts. These have no fabric covering on the sides, which allows for much greater flexibility and reduced stress when subjected to a 30-degree twist.
  
• Material: EPDM rubber is preferred as it better handles the heat generated by the increased stress of a twisted drive compared to traditional neoprene.
  
• Banded vs. Single: Ensure you are using a single belt (or a, accurately matched set) for high-twist applications; banded belts (multiple belts joined together) are not designed for twists. 
  

Conclusion: The Gates Quad-Power 4 (3VX1180/XPZ1180) is likely the best direct alternative for maximum flexibility in a 30-degree twist scenario.

in my recent research, (lots of time on my hands this week, but sadly not at home to work on my little machine) I also looked at PIX Belts,
in their PIX-X'tra series it is an EPDM rubber Raw Edge, the X-Set series shows as wrapped,

their X'tra series shows a blurb *can be requested with Aramid core construction. this i am mostly interested in as the Aramid/kevlar tensile strength is double that of poly and rubber. it resists stretching extremely well aswell. i sent them an email regarding out belt sizes already.
https://www.pixtrans.com/products/indust...-belts.php