Is it easy on some aircraft to catch this fault

W

woxof

Pre-takeoff checklist
Joined
May 6, 2015
Messages
127
Display Name
Display name:
woxof
I believe that the cowl opens up on the Cherokee 140. How easy would it be to look of feel for this fault on the pre-flight inspection? What about other aircraft types?

C-FSAJ, a privately registered PA-28-140 Cherokee, was conducting a recreational flight from Courtney Airpark (CAH3), BC to Pitt Meadows (CYPK), BC with the pilot and one passenger on board. They began the day in CYPK and were on the third and final leg of their round-trip flight. The aircraft departed CAH3 from Runway 13 and climbed straight out with no issues. When the aircraft was level at 2000 feet above sea level (ASL), the pilot requested a clearance through the Comox control zone toward Sechelt and a climb to 3500 feet ASL with Comox air traffic control (ATC). When the aircraft was climbing through 2200 feet ASL, there was an unplanned loss in engine power (AVCO Lycoming O-320-E3D); engine rpm reduced to idle. The pilot began a 180° turn to the right planning to return to CAH3. On seeing the deviation on radar, Comox ATC queried if everything was alright. The pilot stated that they were having engine trouble, planned to land, and were trouble shooting the problem. When asked if they were declaring an emergency, they stated that they were. During the attempts to regain power, the pilot and his passenger (also a trained pilot) noted that as they pulled the throttle in and out, it stuck a few times and then there was no resistance at all. The pilot determined that a return to CAH3 was not possible and decided to ditch just off the shoreline. The main gear touched the water first and when the nose gear contacted the surface, the aircraft flipped over coming to rest inverted in approximately 3 feet of water. The pilot and passenger undid their seatbelts, opened the latch but were unable to open the door. Persons from shore waded out and were able to open the door and both occupants successfully evacuated the aircraft. A police helicopter, local police, fire, and ambulance personnel attended the scene. The pilot and passenger were taken to the local hospital for observation; no injuries were apparent. The aircraft was substantially damaged in the accident and was recovered from the beach 2 days later. The aircraft maintenance engineer who recovered the aircraft determined the nut that connected the throttle cable to the throttle lever had backed off from its respective bolt.
 
Most installations use a cotter pin at the Throttle Cable connection.

That you could tell by feel or possibly visual from below.

A mirror would be r
How deep do you want to go?

Mixture Control secure?

Mag nuts tight?

I would say that rather than a Preflight Insp that an OWNER do a sort of

Progressive Inspection themselves between Required Inspections.

Is the Flight Control attach as much of a concern as the Throttle?

An Owner can do about 98% percent on an Inspection; if they want.
 
Same thing happened to me once years ago in my T-Craft. In my case the throttle stuck where it was still making partial power, enough to reach an airport so it was a non event.

Hard to see even with the cowl open though, as the carburetor is on the bottom of the engine so probably you'd have to remove the lower cowl.
 
Cherokee's are actually relatively easy to check the Throttle and Carb heat connection during preflight. I have caught a broken Carb heat cable this way, and always check when flying an unfamiliar airplane or after maintenance.

I have had the nut come off of a Citabria that was towing me just after I released. I flew my glider for 2.5 hours unaware that the towplane had made a successful landing in a railroad yard. No damage, flew it out after fixing the throttle linkage.

A couple weeks later a friend of mine flew a Champ (one that I was also flying regularly) to a remote strip and while taxing on the strip had the nut fall off. They had to wait for someone else to fly into the strip and help them obtain a new nut so they could fly it out. Fortunatly it was only a couple hours before someone else flew into the strip.

Brian
 
Entirely dependent on the aircraft. Many aircraft can't raise the cowl without removing a bunch of screws. No inte is doing that for preflight, and it would likely introduce bigger problems from loose cowls and such than it would save by finding a loose throttle/mixture cable.
 
This sort of failure is inexcusable. First, because it's a Canadian airplane, there's a requirement in the regulations that is worded this way:

(d) [Any] Work that disturbs engine or flight controls:

[A statement is required] That the system has been inspected for correct assembly and correct locking of any parts disturbed by the maintenance performed, including an operational check for proper sense and range of motion of the engine or flight controls has been accomplished, by at least two persons, and the technical record contains the signatures of both persons.

CAR Standard 571.10(4), Types of Work table.

Second, every annual inspections MUST cover these things. CAR 625 Appendix B:

(g) Engine controls - inspect for defects, improper travel and improper safety locking;

(k) All systems - inspect for improper installation, poor general condition, defects and insecure attachment;

FAR 32 Appendix D has the same things.

Standard practice prohibits self-locking nuts in places like this, too. AC43.13 has this in Section 7-122:

b. Cotter pins are used on aircraft and engine controls, landing gear, and tailwheel assemblies, or any other point where a turning or actuating movement takes place.

Cheap, casual maintenance and inspections. You get what you pay for.
 
It’s good practice to not only check critical items every annual but also at each oil change or anytime you need to pull the cowl.
 
Jeff767 said:
It’s good practice to not only check critical items every annual but also at each oil change or anytime you need to pull the cowl.
Click to expand...
The typical Cessna inspection checklist has "Engine controls and linkage" in the 50-hour inspection column. Oil change stuff.

upload_2020-12-20_13-11-37.png
 
On typical Cessna high wings, not an easy item to check during preflight. Maybe through the cowl flaps on the larger models? I’ll have to look next time.
 
There is an AD on the throttle linkage on the 0-300 /172 which requires castle nut and cotter key be installed.
 
One of the nice things about the Grumman AA-series is that all have cowlings that easily unlatch and open up completely for inspection. It's amazing the stuff you can easily find before it gets wild and wooly when you can stick your head and hands into the engine space. I've found loose baffles, backed out valve cover screws, pushrod seal leaks, oil screen plug leaks, failing exhaust gaskets, all sorts of mysterious oil drips, etc. etc.

Many aircraft, including the Grumman AA-series, have ball-and-socket linkages between the throttle cable and carburetor. Most owners have long since replaced those with a more secure and easy-to-inspect rod end connection.
 
chemgeek said:
Many aircraft, including the Grumman AA-series, have ball-and-socket linkages between the throttle cable and carburetor. Most owners have long since replaced those with a more secure and easy-to-inspect rod end connection.
Click to expand...
The ball-and-socket (Heim joint) has the bolt torqued so that the ball is held firmly against the throttle lever. That way, the bolt doesn't wallow out the hole in the lever. All the wear is on the ball and its socket, and since it's bearing area is so large it lasts a long time. The rod end idea (a fork) requires the bolt be somewhat loose, so the holes in the lever and fork wear out and so does the bolt. I've found such bolts worn nearly halfway through. Carb heat connections are even worse, in most cases, with a thin steel lever having a bolt that is a bit loose in it. Found those with the bolts really badly worn and the hole in the lever worn clear to the edge of the lever. It's obvious that a lot of mechanics just never expect to find anything. So they don't look.

The technology of a fork and bolt was left behind a long, long time ago by automakers. It's subject to easy contamination by dirt, and vibration really does a lot of damage. Automakers can't afford that sort of garbage.

The AD mentioned by Tom references the Cessna Service Information Letter that triggered the AD. It was to replace the bolt and self-locking nut that would work loose with a drilled bolt, castellated nut and cotter pin. There's another Service Bulletin somewhere that demanded a large-diameter washer on the outboard side of the rod end, since after many hours the socket can wear enough that it falls off the ball. Many, many hours. The washer keeps it in place. This begs the question: why isn't the wear caught long before that?
 
You must log in or register to reply here.
Back
Top