# NTSB NYC88IA186: MBB BK-117, N135CP, Manhattan, NY, July 12, 1988

- Type: NTSB incident investigation
- Classification: Incident · No injuries · Incident investigation · Final report
- Date: July 12, 1988, 12:10 local (16:10 UTC)
- Place: Manhattan, NY
- Location: 40.7834° N, 73.9662° W: Placed by OpenAirDocs: center of Manhattan, NY, within about 6 miles (OpenAirDocs)
- Nearby events: https://openairdocs.org/map.md?lat=40.7834&lon=-73.9662&mi=10
- Phase of flight: [Standing](https://openairdocs.org/ntsb-phases/150) (OpenAirDocs' grouping)
- Highest injury: No injuries
- Injuries: 1 uninjured
- Status: Completed, report March 25, 1991
- Report: Approved by Office Director
- NTSB case key (mKey): 36024
- NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=NYC88IA186
- NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/36024/pdf
- Page: https://openairdocs.org/ntsb/NYC88IA186

## Probable cause

FAILURE OF THE MAIN ROTOR BLADE APPEARS TO BE THE RESULT OF A STATIC DOWNWARD BENDING OVERSTRESS, CAUSED BY ANOTHER HELICOPTER HOVERING OVER OR VERY CLOSE TO THE MAIN ROTOR BLADE AS IT WAS IN A STATIC/STOPPED POSITION.

## Sequence of events

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

- Airframe/component/system failure/malfunction, standing - engine(s) not operating
  - rotor system,main rotor blade - overload
  - planning/decision - improper, pilot of other aircraft (cause)

## Analysis

AS THE PLT OF AN S-76 HELICOPTER WAS HOVERING TO PARK NEXT TO A PARKED MBB BK 117 HELICOPTER, N135CP, THE MAIN ROTOR BLADES OF N135CP BEGAN FLAPPING. SUBSEQUENTLY, ONE BLADE FAILED FROM DOWNWARD OVERLOAD, ABOUT 29 INCHES FROM THE MAIN RETAINING PIN CENTER.

## Aircraft

- Registration: [N135CP](https://openairdocs.org/deregistered/N135CP-2012-05-10), registration cancelled 2012-05-10, S/N S-7014, built 1983 (OpenAirDocs)
- Reported make and model: MBB BK-117
- Registry model: [MBB BK 117 A-3](https://openairdocs.org/model/mbb-bk-117-a-3) (registry code 5626015) (OpenAirDocs)
- Registry engine: [Lycoming LTS-101 series](https://openairdocs.org/engine/lycoming-lts-101-series) (registry code 41560, turbo-shaft) (OpenAirDocs)
- Category: Helicopter
- Engines: LYCOMING LTS-101 550 horsepower turbo shaft
- Damage: Minor damage
- Flight: Business, Part 91
- Operator: Colgate Palmolive
- Registered owner: Colgate Palmolive
- Airworthiness certificate: Standard, Normal
- Destination: TETERBORO, NJ

## Flight crew

As NTSB recorded them. NTSB leaves out names.

- Pilot; age 51; commercial, airline transport; airplane ratings: single-engine land, multi-engine land; instrument ratings: airplane, helicopter; medical: class 1, valid medical--w/ waivers/lim; seat: right

## Weather

- Conditions: Day

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.