WPR12CA288

NTSB accident investigation · Dg-Flugzeugbau DG-500MB · Richland, WA · June 24, 2012

Accident · Minor injuriesData collectionFinal report
Date
June 24, 2012, 14:25 local (21:25 UTC)
Place
Richland, WA
Injuries
1 minor
Damage
Substantial damage
Phase of flight
Approach
Aircraft
N505JLDg-Flugzeugbau DG-500MB
Defining event
Approach-VFR pattern final: Loss of lift
Weather
Visual (VMC) · Day
Status
Completed · report October 4, 2012
Report
Approved by Office Director
NTSB office
Western Pacific Region
Parties
Federal Aviation Administration
FAA report
20120624012789A
Case key
84168

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

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Probable cause

The failure of the spoilers to retract because the right wing spoiler’s lower plate became jammed, which resulted in the glider not having enough lift to make it to the runway surface.

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.

Wing structure: spoilersAircraft › Aircraft structures · Unintentional use/operationDg-Flugzeugbau DG-500MB: 1 caseAll aircraft: 8 casesProbable cause
Wing structure: spoilersAircraft › Aircraft structures · Fatigue/wear/corrosionDg-Flugzeugbau DG-500MB: 1 caseAll aircraft: 8 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

In a written statement, the pilot reported that the accident flight was his second flight of the day. After conducting a series of practice maneuvers, he was returning to the airport. The pilot entered a right traffic pattern and configured the glider for landing. With the landing gear extended and the flaps set at 10 degrees, he opened and tested the spoilers. While on the base leg of the traffic pattern, he noticed that the glider was low, and, as he maneuvered onto final approach, he closed the spoilers (forward activation of the lever). The glider’s sink rate was excessive and he observed that the spoilers visually appeared to be deployed although the control lever was in the full-forward (closed) position. He manipulated the lever back and forth, which had no effect on the spoiler position. The glider impacted railroad tracks about 1,000 feet from the approach end of the runway and sustained substantial damage to the fuselage and wings in the accident sequence. A postaccident examination of the glider revealed that the right wing spoiler’s lower plate appeared to have been rubbing the aft spoiler bay wall until it scraped off the resin. It appeared to have scraped enough material off that it caught on a fabric seam (once sealed in the resin) and would not retract. In other words, the spoiler’s lower plate would not push past the catch due to the exposed fabric edge. The location of the scrape marks and the fabric seam put the spoilers at half extension, which is consistent with the lack of performance the pilot reported. The left wing spoiler’s lower plate bushings were tight, with no play.

Factual narrative

In a written statement, the pilot reported that the accident flight was his second flight of the day. After conducting a series of practice maneuvers, he was returning back to the airport. The pilot entered a right traffic pattern and configured the glider for landing. With the landing gear extended and the flaps set at 10 degrees, he opened/tested the spoilers. While on the base leg of the traffic pattern, he noticed the glider was low, and as he maneuvered onto final approach, he closed the spoilers (forward activation of the lever). The glider’s sink rate was excessive and he observed that the spoilers visually appeared to be deployed although the control lever was in the full-forward (closed) position. He manipulated the lever back and forth, which had no effect on the spoiler position. The glider impacted railroad tracks about 1,000 feet from the approach end of the runway and sustained substantial damage to the fuselage and wings in the accident sequence. The pilot opined that the accident was a result of him mixing up the spoiler lever with the flap lever. He thought he was wrongly activating the flap control, not the spoiler control, which were in close proximity to one another. This led to the spoilers remaining deployed during the final approach. An inspector from the Federal Aviation Administration (FAA) performed a post accident examination of the glider. He stated that the right wing spoiler’s lower plate appeared to have been rubbing the aft spoiler bay wall until it scraped off the resin. It appeared to have scrapped enough material that it caught on a fabric seam (once sealed in the resin) and would not retract (would not push past the catch due to the exposed fabric edge. The location of the scrape marks and the fabric seam the spoiler caught on put the spoilers at half extension, which the FAA inspector thought was consistent with the lack of performance the pilot reported. The left wing spoiler’s lower plate bushings were tight, with no play.

Aircraft

Registration
N505JL
Reported as
Dg-Flugzeugbau DG-500MB
Category
Glider
Serial number
5E-187B3
Airframe hours
878
Engine
Technoflug KS-1G-160-R-1, 64 horsepower, reciprocating
Damage
Substantial damage
Flight
Personal · Part 91
Operator
Sls Partnership Ltd
Registered owner
Sls Partnership Ltd
Airworthiness certificate
Special, Experimental (Special)
Last inspection
Annual · November 22, 2011
Departed
RLD · Richland, WA
Destination
RLD · Richland, WA
Flight plan
Unknown
Airport
RLD · Richland Airport, runway 26, 4,000 × 100 ft, asphalt

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
75
Injuries
Minor
Certificate
Commercial
Flight hours
1,303 total · 311 in this make and model

Weather

Conditions
Visual (VMC) · Day
Wind
210° at 10 knots
Visibility
10 statute miles
Lowest ceiling
None
Temperature
79 °F

Docket · 2

The files NTSB released with the investigation on August 2, 2012, on NTSB’s docket system: statements, records, photos and specialists’ reports. 840 KB 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.