CEN16LA267

NTSB accident investigation · Aeronca 7BCM · Longmont, CO · July 16, 2016

Accident · Minor injuriesLimited investigationFinal report
Date
July 16, 2016, 10:20 local (16:20 UTC)
Place
Longmont, CO
Injuries
1 minor
Damage
Substantial damage
Phase of flight
Takeoff
Aircraft
N2576EAeronca 7BCM
Defining event
Takeoff: Loss of engine power (partial)
Weather
Visual (VMC) · Day
Status
Completed · report December 12, 2016
Report
Approved by Office Director
NTSB office
Central Region
Parties
Flight Standards District Office
FAA report
20160716016699A
Case key
93613

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

The pilot's decision to continue the takeoff after observing a partial loss of engine power, the reason for which could not be determined because postaccident examination of the airframe and engine revealed no evidence of mechanical malfunctions or failures.

Findings · 3

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.

Object/animal/substance: wireEnvironmental issues › Physical environment · Contributed to outcomeAeronca 7BCM: 1 caseAll aircraft: 588 cases
Runway/land/takeoff/taxi surfaceEnvironmental issues › Physical environment · Contributed to outcomeAeronca 7BCM: 1 caseAll aircraft: 253 cases

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 commercial pilot was taking off in the light sport aircraft for a local personal flight. The pilot reported that, while attempting to take off from the 4,799-ft-long runway, he noticed a lower-than-normal engine rpm and that the takeoff roll was significantly longer. Despite the extended takeoff roll and low engine rpm, the pilot chose to continue the takeoff. The airplane lifted off and slowly climbed to about 200 ft above ground level. Due to concerns about rising terrain, the pilot chose to make a forced landing, during which the airplane hit power lines. The airplane then skipped across a road and nosed over. Examination of the airframe and engine revealed no evidence of mechanical malfunctions or failures. Carburetor icing was likely not a factor given the environmental conditions at the time of the accident and the pilot's report of a short taxi time.

Factual narrative

On July 16, 2016, about 1020 mountain daylight time, an Aeronca 7BCM airplane, N2576E, impacted terrain while departing from Vance Brand Airport (LMO), Longmont, Colorado. The pilot sustained minor injuries and the airplane was substantially damaged. The airplane was registered to and operated by 2576E LLC under the provisions of 14 Code of Federal Regulations Part 91 as a personal flight. Day visual meteorological conditions existed at the time of the accident and no flight plan had been filed. The local flight was departing at the time of the accident. On the day prior to the accident, the pilot serviced the airplane with 10 gallons of aviation fuel for a total fuel onboard of 13 gallons. The pilot stated that the elapsed time from engine start to takeoff roll was less than 5 minutes. While performing an engine runup at 1,700 rpm, he checked the carburetor heat and magnetos, which he reported as normal. He recalled the wind conditions as calm. During takeoff roll from Runway 29, the pilot observed the engine was only producing about 2,000 rpm, versus the 2,200 rpm he typically noticed. He continued the takeoff and observed a significantly longer takeoff roll. After liftoff, the airplane was unable to climb normally and after reaching about 200 ft agl, the pilot executed a forced landing due to concerns with terrain. During the forced landing, the airplane hit power lines, skipped across a road and nosed over, which damaged both wings. A pilot witness near the departure end of the runway noticed the airplane liftoff much later than he expected, about 3,000 ft down the 4,799 ft long runway. After liftoff, he noticed the airplane climb slowly to about 200 ft and then bank left and descend out of sight. During the takeoff, the witness observed the windsock indicating a tailwind of 3 or 4 knots. At 1014, the weather observation station at LMO reported the following conditions: wind calm, visibility 7 miles, clear skies, temperature 24 degrees C, dew point 14 degrees C, and altimeter setting 29.98 inches of mercury. At 1034, the conditions were wind 100 degrees at 4 knots. Density altitude was calculated to be 7,388 ft. The Federal Aviation Administration (FAA) icing probability chart indicated there was potential for serious carburetor icing at glide power at the time of the accident. FAA inspectors examined the airplane and determined the fuel from the main tank had leaked out while the airplane was inverted after the accident. The gascolator contained about 2 ounces of fuel, which was clear and bright, with no water or debris. No anomalies were noted with the ignition or carburetor systems. Compression testing of the cylinders was accomplished, with normal results. Examination of the airframe and engine revealed no evidence of mechanical malfunctions or failures that would have precluded normal operation.

Aircraft

Registration
N2576E
Reported as
Aeronca 7BCM (NO SERIES)
Category
Airplane
Serial number
7AC-6159
Built
1946
Airframe hours
3,763
Engine
Continental C85-12FT, 85 horsepower, reciprocating
Damage
Substantial damage
Flight
Personal · Part 91
Airworthiness certificate
Standard, Normal
Last inspection
Annual · September 16, 2015 · 4 hours before
Departed
LMO · Longmont, CO
Destination
LMO · Longmont, CO
Airport
LMO · Vance Brand, runway 29, 4,799 × 75 ft, concrete

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
74
Injuries
Minor
Certificates
Flight instructor, Commercial
Airplane ratings
Single-engine land
Medical
Class 3, With waivers/limitations
Last flight review
May 2, 2015
Seat
Front
Restraint
4-point
Flight hours
792 total · 107 in this make and model · 792 as pilot in command · 3 in the last 90 days · 3 in the last 30 days · 1 in the last 24 hours

Weather

Conditions
Visual (VMC) · Day
Wind
100° at 4 knots
Visibility
7 statute miles
Lowest ceiling
None
Temperature
75 °F, dew point 57 °F
Altimeter
29.97 inHg
Observed at
KLMO

Docket · 4

The files NTSB released with the investigation on October 13, 2016, on NTSB’s docket system: statements, records, photos and specialists’ reports. 1.8 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.