Retractor type seat belt shoulder harness in the 2001 cessna 172S aircraft allows both pilot positio...

Narrative:

2001 model yr C-172 south aircraft. New AC total tach time 60 hours. While flying in cruise condition at 3500 ft MSL, light turbulence was experienced. A single instance of clear air downdraft turbulence was experienced. During this instance, both front seat occupants were jarred such that their heads struck the ceiling of the cockpit. Retractor type seat belts (both shoulder harness and lap belt retract) in this 2001 model year C-172 did not restrain front seat crew members from rising vertically to the point where their heads struck the cabin attendant ceiling. This momentary single instance of turbulence also caused other non-restrained objects in the cabin (checklist book and poh) to also strike the ceiling. No injuries were encountered. No loss of aircraft control was encountered. No significant loss of altitude was experienced. Pilot advised ATC of encounter and requested deviation to uca airport 12 mi ahead. Fellow company aircraft approximately 15 miles ahead responded that they were in smooth conditions. A second aircraft also indicated same. Pilot elected to continue flight to intended destination and no additional events encountered. Pre-engine start, pre-takeoff checklist items had all crew members confirm seat-backs in upright position and seat belts secure. During event, rear seat passenger indicated that lap restraint did stop individual half way up from making contact with cockpit ceiling. This seat belt design differs from older model C-172 in that the older model aircraft had a lap and shoulder belt that looped through the buckle to secure. Concern is raised that retraction type lap mechanism response to short duration turbulence in the form of a down draft may be insufficient. Callback conversation with reporter revealed the following information: the belts are connected together and both have retractors installed. They appear to take up the slack in normal operation but did not restrain occupant during a vertical downdraft situation. There is no provision for manually locking the belts in a fixed position. The head to ceiling clearance in this instance was 3 to 4 inches.

Original NASA ASRS Text

Title: RETRACTOR TYPE SEAT BELT SHOULDER HARNESS IN THE 2001 CESSNA 172S ACFT ALLOWS BOTH PLT POSITION OCCUPANTS TO HIT THE CEILING DURING AN ENCOUNTER WITH AN INSTANTANEOUS VERTICAL WIND SHEAR.

Narrative: 2001 MODEL YR C-172 S ACFT. NEW AC TOTAL TACH TIME 60 HRS. WHILE FLYING IN CRUISE CONDITION AT 3500 FT MSL, LIGHT TURB WAS EXPERIENCED. A SINGLE INSTANCE OF CLR AIR DOWNDRAFT TURB WAS EXPERIENCED. DURING THIS INSTANCE, BOTH FRONT SEAT OCCUPANTS WERE JARRED SUCH THAT THEIR HEADS STRUCK THE CEILING OF THE COCKPIT. RETRACTOR TYPE SEAT BELTS (BOTH SHOULDER HARNESS AND LAP BELT RETRACT) IN THIS 2001 MODEL YEAR C-172 DID NOT RESTRAIN FRONT SEAT CREW MEMBERS FROM RISING VERTICALLY TO THE POINT WHERE THEIR HEADS STRUCK THE CAB CEILING. THIS MOMENTARY SINGLE INSTANCE OF TURB ALSO CAUSED OTHER NON-RESTRAINED OBJECTS IN THE CABIN (CHKLIST BOOK AND POH) TO ALSO STRIKE THE CEILING. NO INJURIES WERE ENCOUNTERED. NO LOSS OF ACFT CTL WAS ENCOUNTERED. NO SIGNIFICANT LOSS OF ALTITUDE WAS EXPERIENCED. PLT ADVISED ATC OF ENCOUNTER AND REQUESTED DEVIATION TO UCA ARPT 12 MI AHEAD. FELLOW COMPANY ACFT APPROX 15 MILES AHEAD RESPONDED THAT THEY WERE IN SMOOTH CONDITIONS. A SECOND ACFT ALSO INDICATED SAME. PLT ELECTED TO CONTINUE FLT TO INTENDED DESTINATION AND NO ADDITIONAL EVENTS ENCOUNTERED. PRE-ENG START, PRE-TKOF CHKLIST ITEMS HAD ALL CREW MEMBERS CONFIRM SEAT-BACKS IN UPRIGHT POSITION AND SEAT BELTS SECURE. DURING EVENT, REAR SEAT PAX INDICATED THAT LAP RESTRAINT DID STOP INDIVIDUAL HALF WAY UP FROM MAKING CONTACT WITH COCKPIT CEILING. THIS SEAT BELT DESIGN DIFFERS FROM OLDER MODEL C-172 IN THAT THE OLDER MODEL ACFT HAD A LAP AND SHOULDER BELT THAT LOOPED THROUGH THE BUCKLE TO SECURE. CONCERN IS RAISED THAT RETRACTION TYPE LAP MECHANISM RESPONSE TO SHORT DURATION TURB IN THE FORM OF A DOWN DRAFT MAY BE INSUFFICIENT. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: THE BELTS ARE CONNECTED TOGETHER AND BOTH HAVE RETRACTORS INSTALLED. THEY APPEAR TO TAKE UP THE SLACK IN NORMAL OP BUT DID NOT RESTRAIN OCCUPANT DURING A VERTICAL DOWNDRAFT SIT. THERE IS NO PROVISION FOR MANUALLY LOCKING THE BELTS IN A FIXED POSITION. THE HEAD TO CEILING CLRNC IN THIS INSTANCE WAS 3 TO 4 INCHES.

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.

Attributes
ACN	547768
Time
Date	200203
Day	Sat
Local Time Of Day	0601 To 1200
Place
Locale Reference	airport : uca.airport
State Reference	NY
Altitude	msl single value : 3500
Environment
Flight Conditions	VMC
Weather Elements	Turbulence
Light	Daylight
Aircraft 1
Controlling Facilities	tracon : rme.tracon
Operator	general aviation : personal
Make Model Name	Skyhawk 172/Cutlass 172
Operating Under FAR Part	Part 91
Flight Phase	cruise : level
Flight Plan	VFR
Person 1
Affiliation	company : corporate
Function	flight crew : single pilot
Qualification	pilot : private
Experience	flight time last 90 days : 30 flight time total : 1100 flight time type : 250
ASRS Report	547768
Person 2
Affiliation	government : faa
Function	controller : approach
Events
Anomaly	aircraft equipment problem : critical inflight encounter : turbulence inflight encounter other other anomaly other
Independent Detector	other flight crewa
Resolutory Action	none taken : unable
Supplementary
Problem Areas	Environmental Factor Weather Aircraft
Primary Problem	Aircraft

Retractor type seat belt shoulder harness in the 2001 cessna 172S aircraft allows both pilot position occupants to hit the ceiling during an encounter with an instantaneous vertical wind shear.