De Havilland DHC-8-102 N922HA

Summary

On 17 July 1991 at about 00:25 local time, a De Havilland DHC-8-102 registered N922HA, operated by Henson Airlines, was involved in an incident near Savannah, Georgia, United States. 5 people were on board and nobody was injured. The aircraft was slightly damaged. The NTSB has published a probable cause for this accident; it is quoted in full below.

Date

17 July 1991 at 00:25

Classification

Incident

Location

Savannah, Georgia, United States

Nearest airport

Savannah (SAV)

Coordinates

32.1210, -81.1808

Aircraft

De Havilland DHC-8-102

Registration

N922HA

Category

Airplane

Engines

2

Operator

Henson Airlines

Operating rule

Part 121: Air Carrier

Purpose of flight

Unknown

Phase of flight

Not recorded

Route

Hilton Head Isl → Jacksonville

Aircraft damage

Minor

Weather

VMC

Light

Dusk

NTSB number

ATL91IA134

Nobody was injured.

THE INADEQUATE INSPECTION PROCEDURES WHICH ALLOWED THE LOSS OF TORQUE ON THE TOP RETRACTION FITTING ATTACHMENT BOLT WHICH SUBSEQUENTLY FAILED IN FATIGUE. FACTORS WERE THE LOSS OF HYDRAULIC FLUID THROUGH A SEVERED LINE, AND THE CORROSION OF A HYDRAULIC QUANTITY LIMITING VALVE.

Quoted verbatim from the NTSB record. This site does not paraphrase or interpret it.

Read the full NTSB narrative

AFTER FLT 4317 TOOK OFF, THE MAIN LNDG GEAR DID NOT RETRACT. THE FLT CREW ACCOMPLISHED THE EMERG CHECKLIST, EXTDD THE LNDG GEAR & MADE AN UNEVENTFUL LNDG. AN EXAM OF THE ACFT DISCLOSED THAT THE RGT LNDG GEAR RETRACTION FITTING HAD FAILED & A HYDRAULIC LINE WAS SEVERED. ALSO, THE QUANTITY LIMITING VALVE(S) WERE CORRODED & THE RESPECTIVE PISTON MOVEMENT WAS RESTRICTED. SUBSEQUENTLY, BOTH HYDRAULIC SYSTEMS WERE DRAIN OF FLUID. AN EXAM OF THE FITTING ATTACHMENT BOLTS REVEALED THE TOP BOLT LOST TORQUE & THE BOLT FAILED IN FATIGUE; THE BOTTOM BOLTS FAILED IN OVERLOAD. ADNLY, THE FITTING SPIGOT FAILED DUE TO HYDROGEN EMBRITTLEMENT; AN IMPROVED FITTING HAS BEEN PRODUCED TO CORRECT HYDROGEN EMBRITTLEMENT PROBLEMS. THE OPER CONDUCTED A FLEET CAMPAIGN & FND 13 LOOSE BOLTS IN OTHER 100 SERIES ACFT. SVRL AIRWORTHINESS DIRECTIVES WERE ISSUED TO CORRECT THE LOSS OF TORQUE ON ATTACHMENT BOLTS, WHICH INCLUDED CHECKING THE TORQUE AT THE 300 HR LNDG GEAR INSPN.

Quoted verbatim from the NTSB record.