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Understanding part of an NTSB accident report

MrNomad

Well Known Member
A friend of mine was killed in a Cessna 152 two years ago. NTSB WPR18FA035 report is out and I am vexed by the following paragraph. I realize this is not an RV issue but I am trying to understand where "lint" could come from. Thx.

"The carburetor fuel inlet screen was found properly installed. The fuel inlet screen contained a loosely packed material consistent with lint that constituted approximately 50% of the screen internal volume. The material was submitted to the NTSB Materials Laboratory for identification. The material consisted of two different fibrous materials: one blue, and one reddish-brown in color. A spectrometer was used to collect and process infrared wavelength absorbance spectra of the material; the spectral results indicated that the material was most likely cellulose, which is found in natural plant fibers such as cotton. The material was foreign to the airplane fuel system, and it was not determined when or by what means the lint was introduced into the fuel system."
 
Sounds like a cotton cloth or rag may have been used to clean the inside of one of the fuel tanks or some part of the fuel system previous to the accident. Most likely an edge or some portion of the cloth contacted a rivet or a sharp edge inside and was torn off. That's probably where your lint came from.

Charlie
 
Lint

I suspect it came from either shop disposable towels or rags. Might have cleaned something in the fuel system and wiped it off with the above.
Sorry for your loss.
Duff
 
Lint in fuel system

Sorry for your loss Barry. Clearly anything foreign in the fuel system is bad, and that's very important for all of us, but it does not seem to have caused the engine to stop, based on the information in the report.
 
Very interesting. Tragic. I can see maybe a fueler using a rag or wearing cotton gloves to handle the fuel caps. They become worked and deteriorated, perhaps a piece gets pinched and caught putting the cap back on. Next time the cap is removed the piece falls in and with time breaks down into smaller pieces.
At 65 and 36,000+ hours.....this one really has my attention and I will be rethinking my refueling method. The 152 has a raised refueling port offering some protection from debris falling in, or blown in. Vans is flush. In my hanger I use a small soft carpeted inverted bath mat to protect the wing in front of the port from the nozzle and hose even though I hold both off the wing. Not any more. Seems dumb now.
Thanks for reaching out with your question. It certainly impacted my methods.

R
 
Good question, doesn't the 152 have a collection screen in the gascolator?

So in that case it would have been something from service work downstream of the gascolator. Two colors sounds like a process issue with multiple occurrences.

It is a good reminder to check my servo screen at annual.
 
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screens worked

Good question, doesn't the 152 have a collection screen in the gascolator? ...
Looks to me like the screens worked - the engine kept running. The accident was not caused by any type of engine failure. The engine was turning at impact, according to the report I read.
 
I Had to pop open my fuel tanks to perform a service bulletin before flying, I cleaned the tanks ?very? well with red shop rags. I found red fibers in my fuel filter screen as well as red fibers causing the quick drain to drip. It took several flushings before I got them all out.
 
Lint

Part of my A&P school involved two weeks working with an A&P who maintained a fleet for a university flight school. When he tasked me with opening and inspecting a gascolator, he told me that I'd probably only find lint on the screen. It didn't occur to me at the time to ask where the lint might come from, but it was common enough for him to prepare me to look for it.

Cheers, David
RV-6A - A&P
 
Good question, doesn't the 152 have a collection screen in the gascolator?

So in that case it would have been something from service work downstream of the gascolator. Two colors sounds like a process issue with multiple occurrences.

It is a good reminder to check my services screen at annual.

Looks to me like the screens worked - the engine kept running. The accident was not caused by any type of engine failure. The engine was turning at impact, according to the report I read.

I agree, it doesn't sound like the foreign material in the carb screen was a factor in this unfortunate accident.
In fact, my guess would be that it had been there for a long time since there was no indication of the same material in the gascolator screen or pick-up screens in the fuel tanks. Likely because the gascolator screen was probably getting regularly maintained during inspections, like it is supposed to be, but the inlet screen on the carb. was not. Fairly common, unfortunately.

Good reminder for RV owners. Do you know that the carb. or fuel injection servo you have on your airplane has an inspect-able / cleanable inlet screen?
 
Sorry for the loss of your friend and condolences to all friends and family.

Last part of report is odd, illogical.... This was a clear day... with light winds and they just put this at the end of the report:[/B][/I][Edit: My mistake it was night]
"Spatial Disorientation & Situational Awareness

According to the FAA publication Pilot's Handbook of Aeronautical Knowledge (PHAK, FAA-H-8083-25):

Spatial disorientation specifically refers to the lack of orientation with regard to the position, attitude, or movement of the airplane in space…. During flight in visual meteorological conditions (VMC), the eyes are the major orientation source and usually prevail over false sensations from other sensory systems. When these visual cues are taken away… false sensations can cause a pilot to quickly become disoriented.

The handbook then stated that "Prevention is usually the best remedy for spatial disorientation. Unless a pilot has many hours of training in instrument flight, flight in reduced visibility or at night when the horizon is not visible should be avoided."

The handbook defined situational awareness as the "accurate perception of the operational and environmental factors that affect the airplane, pilot, and passengers during a specific period of time." The handbook stated that a situationally aware pilot "has an overview of the total operation and is not fixated on one perceived significant factor." The handbook stated that "some of the elements inside the airplane to be considered are the status of airplane systems," and cautioned that "an awareness of the environmental conditions of the flight, such as spatial orientation of the airplane, and its relationship to terrain… and airspace must be maintained."


VMC in the pattern it is unlikely there was LOC due to spacial disorientation in my opinion as a CFI. This statement vexes me. Was there a lawsuit? I know there was a C152 accident years ago (in Florida I recall) that resulted in huge awards against Cessna, Lycoming, Marvel Schebler, FBO and anyone else they could think of to sue.....
 
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From the report, "Night visual meteorological conditions prevailed"

Illogical? Spatial disorientation - night, few lights, right hand turn in a high wing airplane. Sorry, not to me.

Merrill
 
From the report, "Night visual meteorological conditions prevailed"

Illogical? Spatial disorientation - night, few lights, right hand turn in a high wing airplane. Sorry, not to me.

Merrill
Thanks I missed the night part. I like how you told me. Ha ha. Not sure what right turn in high wing has to do with it, if you have horizon in your windscreen. If the wing blocks the only reference to ground/horizon yes I can see that being a factor. May be more relevant:

I looked up moon phase at Tehachapi Municipal Airport (KTSP), on that date (google is amazing). It was a very dark night, 1.9% illumination (full moon is 99%).*

The airport is in a rural mountainous area with uneven Horizon and not a lot of ground lights.

He was fairly low time pilot but current and flew a cross country at night in/out of that airport the month before. He had 12 hours of night time.

*As a CFI, early on I did a night flight with student on a full moon night. I cut the flight short. You could see everything. The next night flight a few weeks later it was almost moonless. I had him do touch and goes at an airport away from city lights. Rotating into the dark was an eye opener for him. I used the integrated method and always had my students flying by instruments and visually together always, even day VFR. Doing night TG's at the city airport was less challenging since it was awash with lights.

Lesson dark moonless night taking off into a black hole be ready to fly instruments. I remember taking off from Sedona AZ and it was pitch black. Early in my flying, newly minted Pvt with about the same hours as this Gentleman, took off from New Orleans Lake Front Airport over Lake Pontchartrain. It was pitch black. I remember getting on instruments as my instructor taught me. Once I turned cross wind and went back towards shore and city lights I was fine. In years since there have been a few LOC accidents off of New Orleans Lack Front due to spacial disorientation.
 
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Thanks I missed the night part. I like how you told me. Ha ha. Not sure what right turn in high wing has to do with it, if you have horizon in your windscreen. If the wing blocks the only reference to ground/horizon yes I can see that being a factor. May be more relevant:

I looked up moon phase at Tehachapi Municipal Airport (KTSP), on that date (google is amazing). It was a very dark night, 1.9% illumination (full moon is 99%).*

The airport is in a rural mountainous area with uneven Horizon and not a lot of ground lights.

He was fairly low time pilot but current and flew a cross country at night in/out of that airport the month before. He had 12 hours of night time.

*As a CFI, early on I did a night flight with student on a full moon night. I cut the flight short. You could see everything. The next night flight a few weeks later it was almost moonless. I had him do touch and goes at an airport away from city lights. Rotating into the dark was an eye opener for him. I used the integrated method and always had my students flying by instruments and visually together always, even day VFR. Doing night TG's at the city airport was less challenging since it was awash with lights.

Lesson dark moonless night taking off into a black hole be ready to fly instruments. I remember taking off from Sedona AZ and it was pitch black. Early in my flying, newly minted Pvt with about the same hours as this Gentleman, took off from New Orleans Lake Front Airport over Lake Pontchartrain. It was pitch black. I remember getting on instruments as my instructor taught me. Once I turned cross wind and went back towards shore and city lights I was fine. In years since there have been a few LOC accidents off of New Orleans Lack Front due to spacial disorientation.

I would say that a pilot with just 12 hours of night flight time flying into Tehachapi on a dark, moonless night could truly be challenged. Tehachapi airport is located near the edge of a bowl and there are some hills near the airport that could give some very misleading visual indicators in the dark, especially with the spotty rural lighting in the vicinity.

Skylor
 
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