ERA22LA045

NTSB accident investigation · Cessna 172 · Decatur, GA · November 4, 2021

Accident · Minor injuriesClass 3 · LimitedFinal report
Date
November 4, 2021, 09:47 local (13:47 UTC)
Place
Decatur, GA · In front of 2806 N Decatur Road
Injuries
1 minor
Damage
Substantial damage
Phase of flight
Enroute
Aircraft
N172XXCessna 172
Defining event
Enroute-cruise: Loss of engine power (total)
Weather
Visual (VMC) · Day
Status
Completed
Report
Approved by Office Director
Investigation class
Class 3
NTSB office
Eastern Region Aviation
Parties
FAA/FSDO
FAA report
20211104018909A
Case key
104203

From the NTSB’s public API. By law, NTSB reports can’t be used as evidence in lawsuits over the accident.

On this page

Probable cause

Oil exhaustion due to an oil leak that resulted in a total loss of engine power.

Findings · 2

NTSB’s coded findings. Those marked are part of the probable cause; the rest are factors or other findings. Under each, the cases with the same finding.

Fluids: oilAircraft › Fluids/misc hardware · Fluid levelCessna 172A: 1 caseAll aircraft: 174 casesProbable cause
Engine (reciprocating): recip engine power sectionAircraft › Aircraft power plant · Damaged/degradedCessna 172A: 1 caseAll aircraft: 233 casesProbable cause

Sequence of events

The events NTSB coded, in order, by phase of flight. The defining event is the one that best describes the accident. Under each, the cases with the same event anywhere in their sequence.

Analysis

The student pilot reported that, before takeoff, he added 1 quart of oil, bringing the oil quantity to full capacity. Shortly after takeoff, while the airplane was at an altitude of 1,500 ft mean sea level, the pilot noted that the engine began running roughly, which was followed by a total loss of engine power. He pitched the airplane to attain its best glide airspeed. He descended the airplane for a forced landing to a four-lane road, during which the airplane struck powerlines and came to rest inverted on the road. Postaccident examination of the engine found that crankcase was breached consistent with a catastrophic failure. Additionally, a substantial amount of oil was covering the exterior of the bottom fuselage skin from the engine compartment to the tailcone, fresh oil was noted in the cockpit floor area, and only a minimal amount of oil remained in the engine. Given this information it is most likely that the total loss of engine power occurred due to oil exhaustion, that was precipitated by an oil leak. At the rear portion of the engine, the oil filter adapter and its attached base had separated from the accessory case. Although it is possible that the oil leak emanated from this location, the available evidence for this investigation precluded a definitive determination of the source for the oil leak.

Factual narrative

On November 4, 2021, about 0947 eastern daylight time, a Cessna 172A, N172XX, was substantially damaged when it was involved in an accident near Decatur, Georgia. The student pilot sustained minor injuries. The airplane was operated as a Title 14 Code of Federal Regulations Part 91 personal flight. The student pilot stated that, before takeoff, he added 1 quart of oil, bringing the total quantity to 8 quarts (full capacity). The airplane departed from Dekalb-Peachtree Airport (PDK), Atlanta, Georgia. While the airplane was at an altitude of 1,500 ft mean sea level, the student pilot noted that the engine began running roughly, which was followed by a total loss of engine power. The student pilot pitched the airplane for best glide airspeed and declared an emergency with air traffic control. He subsequently attempted a forced landing to a four-lane road, but the airplane struck powerlines and came to rest inverted on the road. The accident site was located about 5 miles south-southwest of PDK. Postaccident examination of the airplane at the accident site revealed that the exterior surface of the bottom fuselage skin was coated in oil from the engine compartment to the tailcone, and a hole was noted in the crankcase above the No. 6 cylinder. Examination of the airframe and engine after recovery revealed fresh oil on the cockpit floor behind the firewall. In the rear portion of the engine, the oil filter adapter and its attached base had separated from the engine accessory case. The adapter did not appear to be safety wired, per the instructions in the manufacturer’s service bulletin. The separated portion of the oil filter, which was safety wired, exhibited impact damage. The oil suction screen contained some ferrous material, but no contamination was observed in the oil filter element. About 4 to 5 ounces of oil were drained from the oil sump, which contained metal. Examination of the accessory case revealed that the lower portion of the opening, into which the oil filter adapter threads, was fractured away. None of the smeared threads of the accessory case accepted the oil filter adapter, but some of the damaged threads of the oil filter adapter would have threaded into the accessory case. A review of the maintenance records revealed that the airplane’s last annual inspection was completed in January 2014, more than 7.5 years before the accident. The Federal Aviation Administration inspector assigned to this investigation reported that the oil filter adapter was installed “sometime in 2020,” but this installation was not documented in the maintenance records. As part of the National Transportation Safety Board Pilot/Operator Aircraft Accident/Incident report, the student pilot indicated the following: There was evidence of the spin on adapter being over torqued upon installation that cracked the accessory housing, which in turn never leaked but broke free on rotation at PDK. This dumped all eight quarts [of oil] out of a hole over an inch indiameter starving the crank and causing the [connecting] rods to seize. The spin on was installed by the [airframe and powerplant mechanic] that did the 100hr inspection.

Aircraft

Registration
N172XX
Reported as
Cessna 172 (A)
Category
Airplane
Serial number
47123
Built
1959
Airframe hours
4,531
Engine
Continental O-300-C, 145 horsepower, reciprocating
Damage
Substantial damage
Flight
Personal · Part 91
Registered owner
Roberts Christopher B
Airworthiness certificate
Standard, Normal; Standard, Utility
Last inspection
Annual · January 19, 2014 · 181 hours before
Departed
PDK · Atlanta, GA
Destination
PXE · Perry, GA
Airport
PDK · Dekalb-Peachtree
Equipment
Auto-pilot, Handheld GPS, Satellite tracking device, Stall warning system, Video recording device

Matched to the registry by N-number and the event date; the registry’s history has gaps, so older matches can be wrong. Compare the reported make and model.

Flight crew

As NTSB recorded them. NTSB leaves out names.

Role
Pilot
Age
35
Injuries
Minor
Certificate
Student
Medical
Class 1, Without waivers/limitations
Seat
Left
Restraint
Lap only

Weather

Conditions
Visual (VMC) · Day
Wind
40° at 4 knots
Visibility
5 statute miles
Lowest ceiling
3,100 ft overcast
Temperature
45 °F, dew point 43 °F
Altimeter
30.26 inHg
Observed at
KPDK, 5 nm away
METAR
KPDK 041353Z 04004KT 5SM -RA BR FEW009 OVC031 07/06 A3026 RMK AO2 SLP251 P0001 T00720061

Docket · 7

The files NTSB released with the investigation on September 7, 2023, on NTSB’s docket system: statements, records, photos and specialists’ reports. 28.2 MB in all.

FAA reports on this event · 1

The FAA’s own accident and incident reports, matched to the aircraft by N-number and date.