20140617012149A

Accident · Substantial damage

FAA accident report · Schweizer 269C-1 · Allentown, PA · June 17, 2014

Date: June 17, 2014 · 12:10 local
Place: Allentown, PA
Phase of flight: Other, Specify
Operating rules: Pilot school (Part 141)
Operator: GU7S
Damage: Substantial damage
Aircraft: N152CC
NTSB investigation: NTSBERA14LA293
Reported as: Schweizer 269C-1
Reported engine: Lycoming HO-360
People aboard: 1
Fatal injuries: 0
Other injuries: 1
Pilot’s certificates: Airline transport, flight instructor
Pilot’s flight hours: 5,300 total35 in this make and model30 in the last 90 days

N152CCRegistration cancelled Feb 16, 2017 · Schweizer 269C-1S/N 0144 · Built 2002 Airframe modelSchweizer 269C-1 Engine modelLycoming HO-360 seriesReciprocating

From the FAA’s Accident/Incident Data System (AIDS), through its Aviation Safety Information Portal, as reported. The NTSB investigates accidents separately, and its record of an accident is the fuller one. The aircraft is matched to the registry by N-number and event date, checked against the reported make and model; the registry’s history has gaps, so older matches can be wrong. Compare the reported make and model.

What happened

The FAA’s narrative, in sentence case. The FAA writes it in capitals and removes private details.

The ATP sel/mel rated pilot is taking rotorcraft flight instruction. The pilot had completed some solo practice, returned to the tower controlled airport and set down on a taxiway for a frequency change. She experienced some ground resonance and lifted the helicopter, hovertaxied to it's parking spot and set down again. She began the cooldown checklist and estimates that 15-20 seconds elapsed after lowering the collective and applying control friction, the helicopter again experienced ground resonance. She felt that she would not be able to raise the collective due to the friction, and elected to close the throttle. The resonance continued and got worse until the helicopter destroyed itself.

Sikorsky (parent company of aircraft manufacturer shweitzer) engineering suggests that the skid dampers are designed to prevent divergent resonance, and function adequately when properly maintained. NTSB has directed the removal of all skid dampers and transmitting them to Sikorsky for analysis.

As the FAA filed it

THE ATP SEL/MEL RATED PILOT IS TAKING ROTORCRAFT FLIGHT INSTRUCTION. THE PILOT HAD COMPLETED SOME SOLO PRACTICE, RETURNED TO THE TOWER CONTROLLED AIRPORT AND SET DOWN ON A TAXIWAY FOR A FREQUENCY CHANGE. SHE EXPERIENCED SOME GROUND RESONANCE AND LIFTED THE HELICOPTER, HOVERTAXIED TO IT'S PARKING SPOT AND SET DOWN AGAIN. SHE BEGAN THE COOLDOWN CHECKLIST AND ESTIMATES THAT 15-20 SECONDS ELAPSED AFTER LOWERING THE COLLECTIVE AND APPLYING CONTROL FRICTION, THE HELICOPTER AGAIN EXPERIENCED GROUND RESONANCE. SHE FELT THAT SHE WOULD NOT BE ABLE TO RAISE THE COLLECTIVE DUE TO THE FRICTION, AND ELECTED TO CLOSE THE THROTTLE. THE RESONANCE CONTINUED AND GOT WORSE UNTIL THE HELICOPTER DESTROYED ITSELF.

SIKORSKY (PARENT COMPANY OF AIRCRAFT MANUFACTURER SHWEITZER) ENGINEERING SUGGESTS THAT THE SKID DAMPERS ARE DESIGNED TO PREVENT DIVERGENT RESONANCE, AND FUNCTION ADEQUATELY WHEN PROPERLY MAINTAINED. NTSB HAS DIRECTED THE REMOVAL OF ALL SKID DAMPERS AND TRANSMITTING THEM TO SIKORSKY FOR ANALYSIS.

NTSB investigation

The NTSB’s investigation of this event, with its probable cause and findings. Matched to this report by N-number and date.

NTSB ERA14LA293Accident · Minor injuriesLimited investigationFinal reportAllentown, PAInadequate inspection and maintenance of the helicopter’s landing gear dampers, which resulted in ground resonance during helicopter shutdown.Jun 17, 2014 · Substantial damage

Other reports on N152CC · 1

Matched to the same aircraft by N-number and date.

Incident 20111007025359ICruise/Level Flight · Allentown, PAPilot departed abe and was cruising at 1000' on way to xll when the engine suddenly sputtered and the helicopter yawed to the left. He immediately chose a field in which to land and performed an autorotation. The aircraft landed safely but one of the cross…Oct 7, 2011 · Minor damage