LA boo boo???  

TSB report **A11C0079** (27 May 2011, Butler Lake, Ontario) covers an AS 350 B-2 that had been converted from an Arriel to a Honeywell **LTS101-700D-2** under the Soloy STC. The audio and power-loss sequence is the same pattern you described.

**What happened in flight**  

After a steep climb and a rapid level-off at 800 ft, the pilot felt two left yaw kicks and heard the **intermittent high-rotor horn**. That was followed by total engine power loss and the **continuous low-rotor horn**. He autorotated into shallow water. Everyone got out; the tail boom was wrecked.

**How the LTS-101 overspeed system is supposed to work**  

- PT governor holds ~100% Np / ~390 Nr.  

- EOS watches Np. At **109% Np** a solenoid **reduces** fuel; at **106% Np** it restores fuel.  

- If the governor is still failed, the system **cycles**.  

- Horns: intermittent above 410 Nr, continuous below 360 Nr.

**What the TSB found**  

The PT governor spool bearing (PN 2523973N) was destroyed after only **228 hours**. Microscopic diamond particles left in the bearing from manufacture caused abrasive wear, heat, grease breakdown, then bearing failure. With the governor dead, the engine oversped.

The fuel pump still had the original **0.132-inch inducer jet**. Honeywell already knew that EOS cycling with that orifice can spike pressure on the unmetered side of the FCU minimum-pressure valve, close the valve, and flame the engine out. A larger jet prevents that. The EOS box itself tested serviceable.

**Test-cell confirmation**  

With the original governor installed, unloaded Np ran straight through 100% to 109% — governor failed. After an overhauled governor was fitted, Np governed normally at 100%.

**TSB’s chain**  

1. Rapid level-off unloaded the rotor slightly.  

2. Failed PT governor let Np/Nr climb → first yaw kick + high-NR horn.  

3. EOS tripped, bled fuel, Np dropped to 106%, then climbed again → second yaw kick.  

4. On that second cycle the small inducer jet let the min-pressure valve close.  

5. Fuel flow collapsed → flameout → low-NR horn → autorotation.

**Findings in short**  

Cause: failed PT-governor spool bearing (contaminated 2006–2008 Timken bearing).  

Contributor: 0.132-inch fuel-pump inducer jet, which turned EOS cycling into a flameout.

That report is the documented LTS-101 AStar case of “high-rpm horn, then engine dies, then low-rotor horn.”