OpenAirDocs.org

19980627015189A

Accident · Substantial damage
Open the Markdown

FAA accident report · Scwzer G-164B · Oakdale, WA · June 27, 1998

FAA Aviation Safety Information Portal

© OpenStreetMap
Date
June 27, 1998 · 06:30 local
Place
Oakdale, WA
Phase of flight
Forced/Precautionary Landing
Operating rules
Agricultural (Part 137)
Operator
NRVG
Damage
Substantial damage
Aircraft
N7502C
NTSB investigation
NTSBSEA98LA106
Reported as
Scwzer G164B
People aboard
1
Fatal injuries
0
Pilot’s flight hours
19,400 total600 in this make and model200 in the last 90 days
N7502CRegistered now · Schweizer G-164BS/N 817B · Built 1989Airframe modelSchweizer G-164BEngine modelPratt & Whitney R1340 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.

Lost power on takeoff. No further information. (.4)according to the pilot, during takeoff, approximately 10 feet above the ground, the aircraft started backfiring and losing power. He aborted the takeoff, but was unable to get the aircraft stopped before impacting a ditch just off the departure end of the airstrip. A post-accident inspection of the engine by an FAA airworthiness inspector found that a portion of the number three cylinder head casting through which the exhaust valve rocker pin passes had fractured. This allowed the number three cylinder exhaust valve to remain in the closed position during the time that it should have been open, resulting in a loss of power. The rocker box casting was sent to the NTSB metallurgical laboratory for further analysis. That examination revealed that the fracture in the casting was the result of a fatigue crack that originated in the wall of the hole in the casting through which the rocker arm pivot bolt passed. It could not be determined what caused the fatigue crack to initiate.

As the FAA filed it

LOST POWER ON TAKEOFF. NO FURTHER INFORMATION. (.4)ACCORDING TO THE PILOT, DURING TAKEOFF, APPROXIMATELY 10 FEET ABOVE THE GROUND, THE AIRCRAFT STARTED BACKFIRING AND LOSING POWER. HE ABORTED THE TAKEOFF, BUT WAS UNABLE TO GET THE AIRCRAFT STOPPED BEFORE IMPACTING A DITCH JUST OFF THE DEPARTURE END OF THE AIRSTRIP. A POST-ACCIDENT INSPECTION OF THE ENGINE BY AN FAA AIRWORTHINESS INSPECTOR FOUND THAT A PORTION OF THE NUMBER THREE CYLINDER HEAD CASTING THROUGH WHICH THE EXHAUST VALVE ROCKER PIN PASSES HAD FRACTURED. THIS ALLOWED THE NUMBER THREE CYLINDER EXHAUST VALVE TO REMAIN IN THE CLOSED POSITION DURING THE TIME THAT IT SHOULD HAVE BEEN OPEN, RESULTING IN A LOSS OF POWER. THE ROCKER BOX CASTING WAS SENT TO THE NTSB METALLURGICAL LABORATORY FOR FURTHER ANALYSIS. THAT EXAMINATION REVEALED THAT THE FRACTURE IN THE CASTING WAS THE RESULT OF A FATIGUE CRACK THAT ORIGINATED IN THE WALL OF THE HOLE IN THE CASTING THROUGH WHICH THE ROCKER ARM PIVOT BOLT PASSED. IT COULD NOT BE DETERMINED WHAT CAUSED THE FATIGUE CRACK TO INITIATE.

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 SEA98LA106Accident · No injuriesLimited investigationFinal reportOakdale, WAA fatigue failure of the number three cylinder exhaust rocker box assembly, compromising the ability of the exhaust valve to operate. Factors include a ditch at the end of the runway.Jun 27, 1998 · Substantial damage