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The article is very vague on how the radioactivity allows detection of leaking gas. The video at the bottom explains from 7:50 in. Gas pressure pressing on a s

by 46Bit 23d ago

The article is very vague on how the radioactivity allows detection of leaking gas. The video at the bottom explains from 7:50 in. Gas pressure pressing on a spring holds a radiation shield in place. If the gas leaks the shield moves and the radiation can be detected.

tomasphan 23d ago
The titanium spar is filled with gas. If there was a crack in the spar the gas would escape, therefore tripping the pressure sensitive radiation shield. Releasing radiation that can be detected inside the helicopter. Wireless systems aren’t used for opsec reasons.
- sandworm101 23d ago
  Wireless arent used because they need power/wires and are less reliable than IBIS. Civilian versions of sikorsky helos use the same system.
- DoctorOetker 23d ago
  carrying a radiation source doesn't sound very opsec either to be honest...
  - pixl97 23d ago
    Why? It's not like it's gamma radiation.
  - Johnny555 23d ago
    Since the radiation source is only exposed if it's indicating a potential main rotor crack, and it's not a very strong radiation source in the first place (so it's not like it allows long distance tracking), it seems like a minor risk -- if the radioactive capsule is exposed, the pilot is going to be returning to safe place to land. Beta particles typically only travel a few meters in air before they lose most of their energy.
  - deleted 22d ago
    [deleted]
  - kstrauser 22d ago
    Wait until you find out about smoke detectors. Or microwave ovens. Or light bulbs. Or anything with nonzero temperature.
robocat 23d ago
There's a good comment: MH-53E maintainer here. The system is IBIS (Inflight Blade Inspection System) and the little pods are BIM (blade inspection monitors). The box is pretty obvious sitting just behind the main rotor on the deck above the center engine. I found a random picture on the web: https://assets.verticalmag.com/wp-content/uploads/2017/01/MHM_6001.jpg https://assets.verticalmag.com/wp-content/uploads/2017/01/MH... And: The IBIS devices provide in-flight warning of blade failure on various models of helicopters. One device is located on the root of each blade attached to the rotor. The IBIS detects a decrease in pressure in the blades of a CH-53 model helicopter. Any cracks in the blades will result in a decrease in air pressure in the blade. Such cracks could result in structural failure in the blade, thereby resulting in a potentially dangerous operational situation for the helicopter, such as a hard landing and/or injury to the craft and/or personnel up to, and including, death. Each device contains approximately 500 microcuries (18.5 MBq) of strontium-90 (Sr-90) in the form of a rolled metal foil, encased in a small stainless steel protective cylinder about the size of the press button on a ballpoint pen. The external radiation level of the IBIS is 0.8 mR/hr at 3 inches in the normal (shielded) mode, and 75 mR/hr at 12 inches in the failure (extended) mode. From https://public-inspection.federalregister.gov/2019-08531.pdf?1556282725 https://public-inspection.federalregister.gov/2019-08531.pdf...
- laxpri 23d ago
  What does “inches” mean here
  - deleted 23d ago
    [deleted]
  - pachouli-please 23d ago
    Presumably the measure of distance from the source to receive dosages under those conditions.
  - deleted 23d ago
    [deleted]
  - hansvm 23d ago
deleted 23d ago
[deleted]
lstodd 23d ago
Radioactivity has nothing to do with it. Was solved in Mi-6/Mi-8/Mi-26 blades without it.
- m4rtink 22d ago
  Would be actually interesting to know how other helicopters solved this. :)
- loopies 21d ago
  I saw they moved to composite blades but why don't they need such a warning system?

by 46Bit 23d ago

tomasphan 23d ago

The titanium spar is filled with gas. If there was a crack in the spar the gas would escape, therefore tripping the pressure sensitive radiation shield. Releasing radiation that can be detected inside the helicopter. Wireless systems aren’t used for opsec reasons.

sandworm101 23d ago
Wireless arent used because they need power/wires and are less reliable than IBIS. Civilian versions of sikorsky helos use the same system.
DoctorOetker 23d ago
carrying a radiation source doesn't sound very opsec either to be honest...
- pixl97 23d ago
  Why? It's not like it's gamma radiation.
- Johnny555 23d ago
  Since the radiation source is only exposed if it's indicating a potential main rotor crack, and it's not a very strong radiation source in the first place (so it's not like it allows long distance tracking), it seems like a minor risk -- if the radioactive capsule is exposed, the pilot is going to be returning to safe place to land. Beta particles typically only travel a few meters in air before they lose most of their energy.
- deleted 22d ago
  [deleted]
- kstrauser 22d ago
  Wait until you find out about smoke detectors. Or microwave ovens. Or light bulbs. Or anything with nonzero temperature.

robocat 23d ago

There's a good comment: MH-53E maintainer here. The system is IBIS (Inflight Blade Inspection System) and the little pods are BIM (blade inspection monitors). The box is pretty obvious sitting just behind the main rotor on the deck above the center engine. I found a random picture on the web: https://assets.verticalmag.com/wp-content/uploads/2017/01/MHM_6001.jpg https://assets.verticalmag.com/wp-content/uploads/2017/01/MH... And: The IBIS devices provide in-flight warning of blade failure on various models of helicopters. One device is located on the root of each blade attached to the rotor. The IBIS detects a decrease in pressure in the blades of a CH-53 model helicopter. Any cracks in the blades will result in a decrease in air pressure in the blade. Such cracks could result in structural failure in the blade, thereby resulting in a potentially dangerous operational situation for the helicopter, such as a hard landing and/or injury to the craft and/or personnel up to, and including, death. Each device contains approximately 500 microcuries (18.5 MBq) of strontium-90 (Sr-90) in the form of a rolled metal foil, encased in a small stainless steel protective cylinder about the size of the press button on a ballpoint pen. The external radiation level of the IBIS is 0.8 mR/hr at 3 inches in the normal (shielded) mode, and 75 mR/hr at 12 inches in the failure (extended) mode. From https://public-inspection.federalregister.gov/2019-08531.pdf?1556282725 https://public-inspection.federalregister.gov/2019-08531.pdf...

laxpri 23d ago
What does “inches” mean here
- deleted 23d ago
  [deleted]
- pachouli-please 23d ago
  Presumably the measure of distance from the source to receive dosages under those conditions.
- deleted 23d ago
  [deleted]
- hansvm 23d ago

deleted 23d ago

[deleted]

lstodd 23d ago

Radioactivity has nothing to do with it. Was solved in Mi-6/Mi-8/Mi-26 blades without it.

m4rtink 22d ago
Would be actually interesting to know how other helicopters solved this. :)
loopies 21d ago
I saw they moved to composite blades but why don't they need such a warning system?