Air carrier departs after line maintenance. Detect rumbling noise after takeoff. Return land.

Attributes
ACN	179154
Time
Date	199105
Day	Thu
Local Time Of Day	1801 To 2400
Place
Locale Reference	airport : iah
State Reference	TX
Altitude	msl bound lower : 2000 msl bound upper : 2000
Environment
Flight Conditions	Mixed
Light	Night
Aircraft 1
Controlling Facilities	artcc : zny
Operator	common carrier : air carrier
Make Model Name	Light Transport, Low Wing, 2 Turboprop Eng
Flight Phase	climbout : takeoff climbout : initial landing other
Route In Use	enroute : on vectors
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
ASRS Report	179154
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : instrument pilot : commercial
Events
Anomaly	aircraft equipment problem : less severe other anomaly other
Independent Detector	other flight crewa
Resolutory Action	other
Consequence	Other
Supplementary
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	Pilot Deviation

Narrative:

My first officer and I picked up our light transport 15 mins after go time in the rain. The aircraft had just completed a line check, much of which I had been present. When the aircraft was turned over to us I checked the maintenance the release and asked my first officer to get the gear pins and conduct a walk-around while I went to operations for updated WX. Upon my return I did a quick walk-around looking specifically for the gear pins. Found none and proceeded to the cockpit. All proper checklists were completed and the flight departed. After takeoff a distinct rumbling was heard beneath the floor. Even through our headsets, we thought we heard a gear problem. We discovered the gear up and locked with no unusual indications. I immediately requested a return and was vectored for landing on 14L, sidestep 14R iah. The aircraft landed west/O incident and returned to the gate. Investigation disclosed the hydraulic ground safe valve had been left in the maintenance position following the line check disabling the gear doors. The maintenance supervisor signed off anyway and both my first officer and I missed it on the walk-around. Contributing factors were the tardiness of the flight and the rain which made us less likely to stay outside for a thorough preflight.

Original NASA ASRS Text

Title: ACR DEPARTS AFTER LINE MAINTENANCE. DETECT RUMBLING NOISE AFTER TKOF. RETURN LAND.

Narrative: MY F/O AND I PICKED UP OUR LTT 15 MINS AFTER GO TIME IN THE RAIN. THE ACFT HAD JUST COMPLETED A LINE CHK, MUCH OF WHICH I HAD BEEN PRESENT. WHEN THE ACFT WAS TURNED OVER TO US I CHKED THE MAINT THE RELEASE AND ASKED MY F/O TO GET THE GEAR PINS AND CONDUCT A WALK-AROUND WHILE I WENT TO OPS FOR UPDATED WX. UPON MY RETURN I DID A QUICK WALK-AROUND LOOKING SPECIFICALLY FOR THE GEAR PINS. FOUND NONE AND PROCEEDED TO THE COCKPIT. ALL PROPER CHKLISTS WERE COMPLETED AND THE FLT DEPARTED. AFTER TKOF A DISTINCT RUMBLING WAS HEARD BENEATH THE FLOOR. EVEN THROUGH OUR HEADSETS, WE THOUGHT WE HEARD A GEAR PROB. WE DISCOVERED THE GEAR UP AND LOCKED WITH NO UNUSUAL INDICATIONS. I IMMEDIATELY REQUESTED A RETURN AND WAS VECTORED FOR LNDG ON 14L, SIDESTEP 14R IAH. THE ACFT LANDED W/O INCIDENT AND RETURNED TO THE GATE. INVESTIGATION DISCLOSED THE HYD GND SAFE VALVE HAD BEEN LEFT IN THE MAINT POS FOLLOWING THE LINE CHK DISABLING THE GEAR DOORS. THE MAINT SUPVR SIGNED OFF ANYWAY AND BOTH MY F/O AND I MISSED IT ON THE WALK-AROUND. CONTRIBUTING FACTORS WERE THE TARDINESS OF THE FLT AND THE RAIN WHICH MADE US LESS LIKELY TO STAY OUTSIDE FOR A THOROUGH PREFLT.

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.