# NTSB DEN84FTE01: Harper/Cricri MK-12, N42JH, Longmont, CO, May 18, 1984

- Type: NTSB accident investigation
- Classification: Accident · Fatal · Final report
- Date: May 18, 1984, 10:35 local (16:35 UTC)
- Place: Longmont, CO
- Coordinates: 40.169231, -105.109275 (estimated)
- Nearby events: https://openairdocs.org/map.md?lat=40.1692&lon=-105.1093&mi=10
- Phase of flight: [Approach](https://openairdocs.org/ntsb-phases/500) (OpenAirDocs' grouping)
- Highest injury: Fatal
- Injuries: 1 fatal
- Status: Completed
- Report: Approved by Office Director
- NTSB case key (mKey): 16249
- NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=DEN84FTE01
- NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/16249/pdf
- Page: https://openairdocs.org/ntsb/DEN84FTE01

## Sequence of events

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

- Airframe/component/system failure/malfunction, approach - vfr pattern - downwind
  - flight control,aileron attachment - improper (cause)
  - maintenance,modification - improper, pilot in command (cause)
  - flight control,aileron - failure,total (cause)
  - flight control,aileron - separation
  - flt control syst,elevator control - failure,total (cause)
- Loss of control - in flight, approach
- In flight collision with terrain/water, descent - uncontrolled

## Analysis

THE HOMEBUILT ACFT WAS ON DOWNWIND LEG OF THE TRAFFIC PATTERN, AFTER INITIAL TAKEOFF, WHEN IT WENT INTO A DIVE & COLLIDED WITH THE GROUND. A WITNESS SAID HE HEARD A POWER REDUCTION BEFORE THE DIVE & POWER ADDED AGAIN AS IT STARTED DOWN. THE PLT'S SON SAID HIS FATHER HAD CONTROL FLUTTER PROBLEMS AT SPEEDS ABOVE 100 MPH. THIS WAS VERIFIED BY A LOGBOOKENTRY. BY REDUCING SPEED, THE FLUTTER WENT AWAY. THUS, THE FLAPERON (AILERON) PUSH RODS WERE MODIFIED BY THE PLT. THE MODIFICATION CONSISTED OF A DOUBLER, 2 BEARINGS & A 1 INCH HOLE TO RETAIN THE BEARINGS. DURING A POST ACCIDENT INSPECTION, IT WAS FOUND THAT THE BELLCRANK ARM HAD SEPARATED FROM THE BEARING. IT WAS FOUND THAT THE DRILLED HOLE WAS IRREGULAR & LARGE ENOUGH TO ALLOW THE BEARING TO SLIP THRU THE HOLE. THE BEARING WAS THE ONLY MEANS OF RETAINING THE BELLCRANK TO THE FULCRUM POINT. THE RIGHT AILERON AT THE ACCIDENT SCENE WAS SEPARATED FROM THE MAIN WRECKAGE AND THE CONTROL PUSH RODS TO THE ELEVATOR WERE BROKEN AT THE BRACKET ATTACHED TO THE ELEVATOR.

## Aircraft

- Registration: N42JH (not matched to a registry record)
- Reported make and model: HARPER/CRICRI MK-12
- Category: Airplane, amateur-built
- Serial number: 071
- Airframe hours: 104
- Engines: JPX PUL 212 15 horsepower reciprocating
- Damage: Destroyed
- Flight: Personal, Part 91
- Registered owner: James B. Harper
- Airworthiness certificate: Special, Experimental (Special)
- Last inspection: Annual, October 18, 1983, 104 hours before
- Airport: 2V2, Longmont Muni, runway 11, 4,200 × 60 ft, asphalt

## Flight crew

As NTSB recorded them. NTSB leaves out names.

- Pilot; age 52; airline transport; airplane ratings: single-engine land, multi-engine land; instrument ratings: airplane; medical: class 1, valid medical--w/ waivers/lim; seat: center; toxicology performed; flight hours: 12,105 total, 10 in this make and model, 143 in the last 90 days, 40 in the last 30 days

## Weather

- Conditions: Visual (VMC), Day
- Wind: calm
- Visibility: 75 statute miles
- Lowest ceiling: none
- Temperature: 82 °F

## 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 19840518018659A](https://openairdocs.org/incident/19840518018659A), May 18, 1984: Amtr CRICRIMK12, Longmont, CO, Destroyed. It was found that bellcrank on right aileron arm separated from bearing that retained it to fulerm.

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.

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