# NTSB FTW89FA093: MBB BO-105S, N2785B, W Cameron Blk, May 7, 1989

- Type: NTSB accident investigation
- Classification: Accident · Fatal · Field investigation · Final report
- Date: May 7, 1989, 14:04 local (19:04 UTC)
- Place: W Cameron Blk
- Phase of flight: [Enroute](https://openairdocs.org/ntsb-phases/400) (OpenAirDocs' grouping)
- Highest injury: Fatal
- Injuries: 1 fatal
- Status: Completed, report September 9, 1992
- Report: Approved by Office Director
- NTSB case key (mKey): 22771
- NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=FTW89FA093
- NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/22771/pdf
- Page: https://openairdocs.org/ntsb/FTW89FA093

## Probable cause

THE PARTIAL ELECTRICAL FAILURE OF THE MICRO-SWITCH FOR THE OUTBOARD LATERAL GUIDE ASSEMBLY, AND THE INCORRECT GUARD INSTALLED ON THE HYDRAULIC TEST SWITCH, RESULTING IN A TOTAL HYDRAULIC FAILURE. FACTORS WERE: THE INCORRECT INSTALLATION OF THE GUARD BY AN UNKNOWN PERSON, THE FAILURE OF THE COMPANY TO COMPLY WITH THE SPECIFIED SERVICE BULLETIN.

## Sequence of events

In NTSB's coding before 2008 (https://www.ntsb.gov/GILS/Documents/codman.pdf).

- Loss of control - in flight, cruise
  - electrical system - failure,partial (cause)
  - hydraulic system - not switched (cause)
  - hydraulic system - failure,total (cause)
  - maintenance,service bulletin/letter - not performed, company maintenance personnel (contributing factor)
  - electrical system,circuit breaker - popped/tripped
  - maintenance,installation - improper, unknown (contributing factor)
  - remedial action - not possible, pilot in command
- In flight collision with terrain/water, descent - uncontrolled
  - terrain condition - water

## Analysis

THE TWIN ENGINE HELICOPTER WAS IN CRUISE FLIGHT OVER THE GULF OF MEXICO, WHEN IT SUDDENLY PITCHED NOSE DOWN AND DESCENDED UNCONTROLLED TO IMPACT INVERTED INTO THE WATER. IT SANK TO A DEPTH OF APPROXIMATELY 380 FEET. AFTER RECOVERY OF THE HELICOPTER, EXAMINATION REVEALED THAT AN INCORRECT HYDRAULIC SWITCH GUARD HELD THE TEST SWITCH IN THE RESET POSITION, ELECTRICALLY ISOLATING HYDRAULIC SYSTEM NUMBER TWO FROM OPERATION, AND THAT THE HYDRAULIC MODULE WAS IN THE NUMBER 1 SYSTEM. FURTHER INSPECTION AND TESTING FOUND A DEFECTIVE MICRO-SWITCH IN THE OUTBOARD LATERAL GUIDE ASSEMBLY OF THE HYDRAULIC MODULE. ADDITIONALLY, THE OPERATOR HAD NOT COMPLIED WITH A REQUIRED SERVICE BULLETIN FOR THE MODULE.

## Aircraft

- Registration: [N2785B](https://openairdocs.org/deregistered/N2785B-1996-01-26), registration cancelled 1996-01-26, S/N S636 (OpenAirDocs)
- Reported make and model: MBB BO-105S
- Registry model: [Messerschmitt-Boelkow-Blohm BO-105S](https://openairdocs.org/model/messerschmitt-boelkow-blohm-bo-105s) (registry code 5626006) (OpenAirDocs)
- Category: Helicopter
- Serial number: 636
- Airframe hours: 1781
- Engines: ALLISON 250-C20B 420 horsepower turbo shaft
- Damage: Destroyed
- Flight: Part 135
- Operator: Air Logistics
- Registered owner: Mcdonnell Douglas Finance Corp
- Last inspection: AAIP, May 6, 1989, 3 hours before
- Departed: NONE, HI-A330, GM
- Destination: NONE, WC-643, GM
- Flight plan: Company VFR
- Airport: NONE

## Flight crew

As NTSB recorded them. NTSB leaves out names.

- Pilot; age 51; flight instructor, commercial; airplane ratings: single-engine land; instrument ratings: helicopter; medical: class 1, valid medical--w/ waivers/lim; seat: right; toxicology performed; flight hours: 7,459 total, 2,397 in this make and model, 6,526 as pilot in command, 168 in the last 90 days, 43 in the last 30 days, 4 in the last 24 hours

## Weather

- Conditions: Visual (VMC), Day
- Wind: calm
- Visibility: 25 statute miles
- Lowest ceiling: none
- Temperature: 82 °F, dew point 63 °F
- Altimeter: 30.00 inHg

## FAA reports on this event (1)

The FAA's own accident and incident reports, matched to the aircraft by N-number and date (OpenAirDocs).

- [Accident 19890507010829A](https://openairdocs.org/incident/19890507010829A), May 7, 1989: Bolkms BO105CBS, West Cameron Bl, LA, Destroyed, 1 fatal. Impacted inverted into gulf waters,no pilot warning but scream on radio. Possible rotor blade or blades separating

## Other investigations on N2785B (1)

From the NTSB's public API. Aircraft are matched to registry aircraft by N-number and event date, checked against the reported serial number, make and model; the registry's history has gaps, so older matches can be wrong. Compare the reported make and model.

- [NTSB FTW89LA031](https://openairdocs.org/ntsb/FTW89LA031), Dec 5, 1988: MBB BO-105 (N2785B), South Marsh 113, substantial damage. Probable cause: FAILURE AND SEPARATION OF ONE OF THE TAIL ROTOR BLADES FOR UNDETERMINED REASONS. THR RESULTING IMBALANCE AND VIBRATION CAUSED THE SEPARATION OF THE 90 DEGREE GEARBOX AND A PORTION OF THE VERTICAL…

From the NTSB's public API. Aircraft are matched to registry aircraft by N-number and event date, checked against the reported serial number, make and model; the registry's history has gaps, so older matches can be wrong. Compare the reported make and model.

---
OpenAirDocs.org is an independent research project of [Contrail Labs](https://contraillabs.com/). It is not affiliated with the FAA or the NTSB. Source documents are U.S. government works in the public domain.