Piper arrow aircraft in cruise, reporter pilot felt thump in airframe and suspects it was the nose g...

Attributes
ACN	385271
Time
Date	199711
Day	Mon
Local Time Of Day	1801 To 2400
Place
Locale Reference	airport : bur
State Reference	CA
Altitude	agl bound lower : 0 agl bound upper : 4000
Environment
Flight Conditions	Marginal
Light	Night
Aircraft 1
Controlling Facilities	tracon : lax
Operator	general aviation : personal
Make Model Name	PA-28 Cherokee Arrow IV
Operating Under FAR Part	Part 91
Flight Phase	cruise other descent : approach landing other
Flight Plan	IFR
Person 1
Affiliation	Other
Function	flight crew : single pilot
Qualification	pilot : instrument pilot : private
Experience	flight time last 90 days : 15 flight time total : 546 flight time type : 242
ASRS Report	385271
Person 2
Affiliation	government : faa
Function	controller : local
Qualification	controller : non radar
Events
Anomaly	aircraft equipment problem : critical other anomaly other
Independent Detector	aircraft equipment other aircraft equipment : unspecified other flight crewa
Resolutory Action	flight crew : declared emergency none taken : unable
Consequence	other
Supplementary
Primary Problem	Aircraft

Narrative:

Departed el monte, ca, for IFR proficiency flight. While en route to smo for VOR runway 21 approach, felt slight thump in airframe. All gauges appeared normal, flight characteristics normal, engine operation normal. Assumed possible bird strike. Vectored onto approach, at FAF gear extension failed to show down and locked nose gear. Approach terminated in visual conditions. Low pass over smo, ground observers reported gear down. Standard emergency gear checklist executed including: check indicator bulbs, check circuit breakers, cycle gear, emergency gear extension maneuvers (fishtailing, high-G climbs/dives, etc). Continued failure to get positive indication of nose gear locked in place. Approached bur in visual conditions. Executed a single low pass over bur runway 8. Ground observers again reported gear appeared down. Briefed copilot for landing: cockpit secured, emergency landing procedures reviewed. Executed soft-field lndgs, shut off electrical equipment and attempted fuel shutoff on short final. Engine stopped very short final (mixture to idle cutoff). Couldn't locate release mechanism on fuel shutoff/tank select switch, even though I knew where it was, so fuel main was not shut off. Door opened prior to touchdown. Nose held off as long as possible. Nose gear collapsed when it finally came down, nose settled to runway and aircraft slid to a stop. Exited aircraft expeditiously, no fire damage. Aircraft sustained damage to lower cowling nose gear mechanism and 1 propeller blade (possibly due to windmilling, as the engine was shut down prior to touch down). Believe that 'thump' was retraction/extension spring failing in-flight. Mechanic also reported no hydraulic pressure on inspection the following day. This may have been due to some structural failure caused by the breaking spring, or may have been a separate failure. Approach control and bur controllers provided superb assistance. Bur emergency/fire crews were extremely professional. Much thanks to everyone who provided assistance.

Original NASA ASRS Text

Title: PIPER ARROW ACFT IN CRUISE, RPTR PLT FELT THUMP IN AIRFRAME AND SUSPECTS IT WAS THE NOSE GEAR RETRACTION EXTENSION SPRING BREAKING, BECAUSE ON LNDG THE NOSE GEAR COLLAPSED. RPTR PLT HAD PREPARED FOR THE EMER LNDG.

Narrative: DEPARTED EL MONTE, CA, FOR IFR PROFICIENCY FLT. WHILE ENRTE TO SMO FOR VOR RWY 21 APCH, FELT SLIGHT THUMP IN AIRFRAME. ALL GAUGES APPEARED NORMAL, FLT CHARACTERISTICS NORMAL, ENG OP NORMAL. ASSUMED POSSIBLE BIRD STRIKE. VECTORED ONTO APCH, AT FAF GEAR EXTENSION FAILED TO SHOW DOWN AND LOCKED NOSE GEAR. APCH TERMINATED IN VISUAL CONDITIONS. LOW PASS OVER SMO, GND OBSERVERS RPTED GEAR DOWN. STANDARD EMER GEAR CHKLIST EXECUTED INCLUDING: CHK INDICATOR BULBS, CHK CIRCUIT BREAKERS, CYCLE GEAR, EMER GEAR EXTENSION MANEUVERS (FISHTAILING, HIGH-G CLBS/DIVES, ETC). CONTINUED FAILURE TO GET POSITIVE INDICATION OF NOSE GEAR LOCKED IN PLACE. APCHED BUR IN VISUAL CONDITIONS. EXECUTED A SINGLE LOW PASS OVER BUR RWY 8. GND OBSERVERS AGAIN RPTED GEAR APPEARED DOWN. BRIEFED COPLT FOR LNDG: COCKPIT SECURED, EMER LNDG PROCS REVIEWED. EXECUTED SOFT-FIELD LNDGS, SHUT OFF ELECTRICAL EQUIP AND ATTEMPTED FUEL SHUTOFF ON SHORT FINAL. ENG STOPPED VERY SHORT FINAL (MIXTURE TO IDLE CUTOFF). COULDN'T LOCATE RELEASE MECHANISM ON FUEL SHUTOFF/TANK SELECT SWITCH, EVEN THOUGH I KNEW WHERE IT WAS, SO FUEL MAIN WAS NOT SHUT OFF. DOOR OPENED PRIOR TO TOUCHDOWN. NOSE HELD OFF AS LONG AS POSSIBLE. NOSE GEAR COLLAPSED WHEN IT FINALLY CAME DOWN, NOSE SETTLED TO RWY AND ACFT SLID TO A STOP. EXITED ACFT EXPEDITIOUSLY, NO FIRE DAMAGE. ACFT SUSTAINED DAMAGE TO LOWER COWLING NOSE GEAR MECHANISM AND 1 PROP BLADE (POSSIBLY DUE TO WINDMILLING, AS THE ENG WAS SHUT DOWN PRIOR TO TOUCH DOWN). BELIEVE THAT 'THUMP' WAS RETRACTION/EXTENSION SPRING FAILING INFLT. MECH ALSO RPTED NO HYD PRESSURE ON INSPECTION THE FOLLOWING DAY. THIS MAY HAVE BEEN DUE TO SOME STRUCTURAL FAILURE CAUSED BY THE BREAKING SPRING, OR MAY HAVE BEEN A SEPARATE FAILURE. APCH CTL AND BUR CTLRS PROVIDED SUPERB ASSISTANCE. BUR EMER/FIRE CREWS WERE EXTREMELY PROFESSIONAL. MUCH THANKS TO EVERYONE WHO PROVIDED ASSISTANCE.

Data retrieved from NASA's ASRS site as of July 2007 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.

Piper arrow aircraft in cruise, reporter pilot felt thump in airframe and suspects it was the nose gear retraction extension spring breaking, because on landing the nose gear collapsed. Reporter pilot had prepared for the emergency landing.