Mbb BO-105S accident near Ponce, Puerto Rico, January 12, 2006
On January 12, 2006 at about 7:43 am local time, a Mbb BO-105S (helicopter), registered N495LF, was substantially damaged in an accident near Ponce, Puerto Rico. It was flown under charter and air-taxi rules (Part 135). 1 person had minor injuries; 3 others were unhurt. The weather was visual conditions (good weather).
The NTSB's probable cause their words, unchanged
A loose B-nut on the PC line connecting the power turbine governor (PTGOV) to the fuel control unit (FCU) that created a leak and caused the engine to roll back to an idle condition, causing a low hydraulic system pressure and subsequent control lock. A contributing factor was the unsuitable terrain (construction area) on which to make a forced landing.
Source: NTSB aviation accident database, copy made October 5, 2026. Docket and reports at the NTSB.
What the record shows
- Date
- January 12, 2006 · about 7:43 am local time
- Place
- Ponce, Puerto Rico · map
- Type
- Accident
- Injuries
- 1 person had minor injuries; 3 others were unhurt.
- Weather
- visual conditions (good weather)
- Aircraft
- Mbb BO-105S
- Registration
- N495LF · no longer on the register · serial S645
- Damage
- Substantial damage
- Flight
- Flight · charter and air-taxi rules (Part 135)
The NTSB's narrative final · quoted from the NTSB record
After the patient was placed aboard the helicopter, the pilot started the engines and performed a hover check. He then moved the helicopter forward to gain airspeed and initiated a climb to cruise altitude. After reaching an altitude of about 100 feet, the main rotor rpm light and audio warning system activated, and the number 2 engine N1 rpm and torque began to decay. The pilot attempted to regain normal engine parameters, but was unable to regain engine rpm. The pilot maneuvered to avoid several light poles as he attempted to land in a parking lot. By this time, main rotor rpm had bled off sufficiently to prevent the hydraulic pumps from pressurizing the hydraulic system, and all flight controls locked is a slight right banked attitude. This prevented the helicopter from reaching the parking lot. The helicopter impacted a construction area in a right bank, nose down attitude. An on-site and later follow-up investigation by FAA and Rolls-Royce investigators revealed a B-nut on the Pc line connecting the power turbine governor (PTGOV) to the fuel control unit (FCU) had become loose at the T-fitting end. It was partially torqued and could be moved with the fingers. The female end was threaded onto the male end three-quarters of a turn. There was no cross-threading. The torque stripe was broken. According to Rolls-Royce Allison, "This line serves a critical function to the engine control system and when leakage occurs will cause the engine to roll back to an idle or near idle condition."
The complete narrative as the NTSB published it. The NTSB's docket holds the report as a PDF and any photographs, statements and other documents from the investigation.
The factual record from the NTSB's investigation tables, in plain English
Pilot
- Certificate: commercial pilot, sport pilot
- Ratings: instrument: helicopter; rotorcraft: helicopter
- Flight time: 4,475 hours in all; 252 in this make and model; 46 in the last 90 days; 13 in the last 30 days; 3,151 as pilot in command
- Last flight review: February 1, 2005
- Medical certificate: Class 3 (with waivers/limitations)
- Seat: rear
- Injury: minor injuries
The aircraft
- Airframe total time: 7,566 hours
- Last inspection: annual inspection, December 1, 2005
- Maximum gross weight: 5,512 lb
- Seats: 3
- Landing gear: fixed
- Engine 1: Allison 250-C20B (turboshaft); 0 hours total
- Engine 2: Allison 250-C20B (turboshaft); 0 hours total
The flight
- Departed from: Ponce PR at 7:43 am
- Destination: San Juan PR
Weather at the time
- Light: night
- Wind: from 120° at 6 knots
- Visibility: 10 statute miles
- Sky: clear
- Temperature: 70°F (21°C), dew point 64°F (18°C)
- Altimeter: 29.97 inHg
- Observation at 7:50 am from TJPS
Injuries
| Fatal | Serious | Minor | None | |
|---|---|---|---|---|
| Crew | 1 | 2 | ||
| Passengers | 1 |
Documents from the investigation the NTSB's docket: the evidence folder behind the report
The docket, the folder of records gathered during an investigation (maintenance records, photographs, witness statements, examinations), has not been read from the NTSB for this case yet; the list appears here once it has. Open the docket at the NTSB.
Everything on this page comes from the NTSB's public records. The narrative, probable cause and findings are the NTSB's own words; the coded tables behind the report are written out in plain English, with pilots' ages, home towns and medical details left out. The documents and photographs are the NTSB's docket, shown as the NTSB released them. This site's own text never names anyone involved. A preliminary report can change; the final report usually follows one to two years later, and the page is refreshed when it does.