NTSB Safety Alert SA-075 - Pilots Ensure Your Fuel Selector Works

PILOTS : Ensure Your Fuel

Selector Works

Worn components can lead to fuel starvation and

sudden loss of engine power

The problem

Worn fuel selectors have led to fuel starvation and loss of engine power, resulting in serious and fatal injuries.

As fuel selectors wear, the fuel selector handles may be difficult or even impossible to turn. If a pilot applies too much

force, the internal components can fracture and obstruct the fuel flow, resulting in a total loss of engine power.

In addition, worn detents could make it difficult for a pilot to properly position the fuel selector to the desired tank.

Positioning the fuel selector incorrectly to an empty tank or in between tanks could ultimately starve the engine of fuel.

Related accidents

Since 2008, the National Transportation Safety Board (NTSB) has cited the fuel selector in 104 accidents; 63 of those

accidents involved incorrect use/operation of the fuel selector, and 28 cited degraded function of the fuel selector. Typically,

these types of accidents result in fuel starvation and loss of engine power.

During the initial climb after a touch-and-go landing in a

Piper PA-38-112, the flight instructor reported an emer -

gency and indicated that he would return to the airport.

The airplane then spun to the left and impacted a marsh.

The airplane was destroyed (figure 1); the flight instruc -

tor sustained serious injuries, and the student pilot died.

Although the fuel selector handle was positioned to the

right main fuel tank, an insert in the fuel selector had

fractured into multiple pieces that showed overstress

and wear (figure 2, next page). The fuel selector handle

likely had been difficult to move for some time, and ex -

cessive force would have been required to move the han -

dle from one position to another, thus causing the wear.

The failure of the fuel selector valve in a position that September 2018

HIGHWAY

MARINE

RAILROAD

PIPELINE

AVIATION

SAFETY

ALERT 075

Figure 1. Photograph of accident airplane.

2 / NTSB Safety Alert 075 / September 2018restricted fuel flow to the engine led to the total loss of

engine power due to fuel starvation. The operator failed

to detect and resolve the wear of the fuel selector valve.

(ERA17FA112 )

The pilot of a Mooney M20 airplane reported that, during

the initial climb from the airport, he noted the engine

power slowing, turned on the boost pump, checked the

magnetos and fuel mixture, and then attempted to switch

the fuel selector to the other fuel tank, which had usable

fuel. The engine experienced a total loss of power, and

the airplane impacted the ground. A passenger sustained

minor injuries, and the pilot and another passenger were

uninjured. The fuel selector handle screw was loose

and prevented the fuel selector from moving to the fuel

tank position for the tank with usable fuel, resulting in

fuel starvation and the subsequent total loss of engine

power (see figure 3). ( GAA17CA260 ) A witness observed the pilot of a Piper PA-28-140

airplane perform an engine run up, and two witnesses

reported that the takeoff sounded normal. However, after

they did not hear the airplane continue around the airport

traffic pattern, one of the witnesses located the wreck -

age at the end of the runway and saw that fuel was flow -

ing out of the wing area. The airplane was substantially

damaged when it collided with trees and terrain (figure

4), and the private pilot died. Although the fuel selector

valve handle was in the right tank position at the time

of the accident, testing of the valve with air indicated

that the valve was closed. The selector valve was stiff

to rotate, and positive engagement of the detents could

not be consistently obtained. Disassembly of the valve

revealed rotational scoring in the valve and on the plug

cock, which had heavily worn detents (figure 5). Debris

was also found in the valve and was the result of exces -

sive wear. Both the owner, who was also the operator,

and maintenance personnel stated that they checked the

fuel selector valve during an annual inspection that was

completed about 11 hours before the accident. The to -

tal loss of engine power after takeoff occurred due to

fuel starvation as a result of excessive wear of the fuel

selector valve. Also causal was the owner/operator and

maintenance personnel's inadequate maintenance and

inadequate postmaintenance inspection. ( ERA15FA128 )

Figure 3. Photograph of fuel selector.

(Source: FAA)Figure 4.

Photograph of

accident airplane.

Figure 5. Plug

cock showing

discoloration,

scoring, wear,

debris, and a worn

detent.

Figure 2. Fuel selector

valve housing and

section of selector

handle (above) and fuel

selector insert with

fractured pieces (right).

NTSB Safety Alert 075 / September 2018 / 3

What can pilots do?

Check the fuel selectors for proper operation during your preflight

assessment, ensuring that the fuel selector moves freely and stays in the

correct detent when selected and that fuel selector placards are accurate

and legible.

Do not force a handle that is difficult to turn; it could lead to fractured

components inside the fuel selector that may prevent proper operation.

Do not fly if your fuel selector exhibits any of the following:

• Sticking and binding,

• Requires greater-than-average pressure to turn or move, or

• Worn detents that do not stop the selector in the desired position.

If you encounter any problems with the proper operation of the fuel selector,

do not attempt the flight. Report the anomaly to maintenance personnel for

inspection or repair.

Be informed and review and comply with any applicable airworthiness

directives and service bulletins regarding the fuel selector and components.

4 / NTSB Safety Alert 075 / September 2018Interested in more information?

The Federal Aviation Administration’s (FAA) Airplane

Flying Handbook, FAA-H-8083-3B, Chapter 2, “Ground

Operations,” page 2-3, contains tips for pilots performing preflight assessments, including checking the fuel selectors for proper operation in all positions, including the OFF position. The handbook notes that “[s]tiff fuel selectors or where the tank position is not legible or lacking detents are unacceptable.” In addition, your airplane flight manual/pilot operating handbook will also likely include instructions in the preflight checklist regarding checking the fuel selector valve.

FAA Special Air worthiness Inform ation Bulletin (SAIB)

CE-14-22 , “Fuel Selector/Shut-Off Valve,” alerts owners

and operators of certain Piper model airplanes that the fuel selector valve may bind when switching fuel tanks and can cause a loss of power in flight. To reduce the possibility of binding in flight, the SAIB recommends inspection and maintenance of fuel selector valves.The Experimental Aircraft Association article “Avoiding Fuel Related Problems ” indicates that fuel problems

can occur due to malfunction or failure of a fuel system component or poor preventative maintenance and cites situations with fuel selector handles that were difficult to turn.

A companion video to this safety alert can be accessed

from the Safety Alerts web page.

The reports for the accidents referenced in this safety

alert are accessible by NTSB accident number from the Aviation Accident Database link, and each accident’s public docket is accessible from the

Accident Dock ets

link for the Docket Management System.

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provides convenient access to NTSB aviation safety products. This Safety

Alert and others can be accessed from the Aviation Safety Alerts link at

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The NTSB is an independent federal agency charged by Congress with investigating every civil aviation

accident in the United States and significant accidents in other modes of transportation—highway, marine, railroad, and pipeline. The NTSB determines the probable cause of the accidents and issues safety

recommendations aimed at preventing future accidents. For more information, visit www.ntsb.gov .