Highly customized experimental fatally crashed, 31-MAY-14, NTSB report has been released.

The pilot/builder who rented a T-hangar next to me (Newport City, Oregon) died because of probable incorrect engine maintenance on an RV-10. Every time he departed or landed the aircraft sounded like $h:t . Lots of missing and backfiring. He used to come over and borrow tools and/or say hello, I did not know him very well. However, I feel bad about what happened. But, was preventable from many people's perspective including NTSB. Daughter and him passed, wife miraculously lived from back seat. Completely terrible and tragically hard to imagine. Where there's smoke there's fire. Anybody, I believe, can drift into denial about aircraft maintenance. I flew once with a bad cylinder, which I was told was making a "weird" noise by line personnel, I refused to believe it because the Jug only had 160 hours on it. Later the piston shredded and the engine required an overhaul/ repair. Big lesson I always think about.

http://www.newportnewstimes.com/v2_news_articles.php?heading=0&story_id=47802&page=86


NTSB Identification: WPR14FA218
14 CFR Part 91: General Aviation
Accident occurred Saturday, May 31, 2014 in Toledo, OR
Probable Cause Approval Date: 04/07/2015
Aircraft: NEBERT VANS RV-10, registration: N62DN
Injuries: 2 Fatal, 1 Serious.
NTSB investigators either traveled in support of this investigation or conducted a significant amount of investigative work without any travel, and used data obtained from various sources to prepare this aircraft accident report.

The pilot, who was also the builder of the experimental kit airplane, departed for a cross-country flight from his home airport. The passenger reported that, following a normal departure, the airplane continued the takeoff climb through some cloud wisps and ascended above a lower cloud cover with an overcast layer above. Suddenly, the engine experienced a total loss of power. The pilot maneuvered the airplane toward the closest airport, but, when he realized that the airplane would not be able to glide to the airport, he attempted to make an off-airport landing. The airplane stalled and then collided with terrain in an open area of a paper mill. Ground scar analysis and wreckage fragmentation revealed that the airplane descended in a steep, near-vertical, nose-down, left-wing-down attitude before it impacted terrain.The pilot installed a fuel flow transducer about 2 to 3 weeks before the accident and used heavy applications of room temperature vulcanization (RTV) silicone to seal the fuel lines. A friend of the pilot, who was also a mechanic, reported that he had observed the pilot about a year earlier using heavy applications of RTV silicone to seal parts during a condition inspection and that he had mentioned to the pilot that this was an improper practice. A bead of RTV silicone was found in the fuel line, and it is likely that it blocked the inlet of the transducer and starved the engine of fuel. Additionally, subsequent to the loss of engine power, the pilot failed to maintain sufficient airspeed while maneuvering to locate a suitable off-airport landing site and flew the airplane beyond its critical angle-of-attack, which resulted in a stall and loss of airplane control.

The National Transportation Safety Board determines the probable cause(s) of this accident as follows:
A total loss of engine power due to fuel starvation because of a blocked fuel line that resulted from the pilot’s improper maintenance practices and the pilot’s subsequent failure to maintain adequate airspeed while attempting a forced landing, which led to the airplane exceeding its critical angle-of-attack and experiencing an aerodynamic stall.

Is that saying he used silicone for thread tape? I can't see where else you could use it on a fuel line.

Nosedragger wrote:Is that saying he used silicone for thread tape? I can't see where else you could use it on a fuel line.

I assume so. He must have really goojed it on there. Either way, bad practice to use silicone. I'm not sure if it's correct either, but I use a PTFE thread dope on my NPT fittings. It never solidifies and would make it through a fuel system okay, though maybe not a fine filter, I dunno. You'd have to really over apply to have enough to do that.

Btw, full report here for those wondering where this detail came from.

Over the years we have removed little specks of RTV in fuel systems, oil filters, hydraulic filters, etc. in customer's aircrafts. I never use on my aircraft in those applications, however.

BTW...

There is an SB from Continental to stop using RTV on cylinder bases. http://www.tcmlink.com/pdf2/sb96-7c.pdf. The SB was modified a few times. The reason is loosing torque due to the RTV.

Just last year an IO470 came in for an annual and it had RTV all over the cylinders bases, return oil lines, etc. I found RTV in the oil filters etc. Good way to ruin an engine by getting a chuck of RTV in an oil passage. We had to remove the cylinder and service per http://www.tcmlink.com/pdf2/sb96-7c.pdf and SM.

8GCBC wrote:Over the years we have removed little specks of RTV in fuel systems, oil filters, hydraulic filters, etc. in customer's aircrafts. I never use on my aircraft in those applications, however.

BTW...

There is an SB from Continental to stop using RTV on cylinder bases. http://www.tcmlink.com/pdf2/sb96-7c.pdf. The SB was modified a few times. The reason is loosing torque due to the RTV.

Just last year an IO470 came in for an annual and it had RTV all over the cylinders bases, return oil lines, etc. I found RTV in the oil filters etc. Good way to ruin an engine by getting a chuck of RTV in an oil passage. We had to remove the cylinder and service per http://www.tcmlink.com/pdf2/sb96-7c.pdf and SM.

I recently learned that same SB from Graham at NW Air Repair. Apparently cylinders should use no gasket material at all, as it can compress over time, reducing the effective torque of the base nuts and creating some dangerous and damaging slop. At least that's how I understood it.

The case and cylinders have a nice beveled/nested fit anyway that seal naturally with some torque.

Zzz wrote:

8GCBC wrote:Over the years we have removed little specks of RTV in fuel systems, oil filters, hydraulic filters, etc. in customer's aircrafts. I never use on my aircraft in those applications, however.

BTW...

There is an SB from Continental to stop using RTV on cylinder bases. http://www.tcmlink.com/pdf2/sb96-7c.pdf. The SB was modified a few times. The reason is loosing torque due to the RTV.

Just last year an IO470 came in for an annual and it had RTV all over the cylinders bases, return oil lines, etc. I found RTV in the oil filters etc. Good way to ruin an engine by getting a chuck of RTV in an oil passage. We had to remove the cylinder and service per http://www.tcmlink.com/pdf2/sb96-7c.pdf and SM.

I recently learned that same SB from Graham at NW Air Repair. Apparently cylinders should use no gasket material at all, as it can compress over time, reducing the effective torque of the base nuts and creating some dangerous and damaging slop. At least that's how I understood it.

The case and cylinders have a nice beveled/nested fit anyway that seal naturally with some torque.

Also, improper torque was the factor in an AZTEC PA-23-250C losing a front cylinder over Maui. The pilot (an instructor I knew) flew her home with oil all over the aircraft back to Honolulu. I was standing by the hangar and was wondering why all the fire/rescue trucks were following the AZTEC while it taxied off the runway. Apparently, the pilot called in an emergency. Great bird! The engine just had a top overhaul and other torques were apparently checked and were fond loose from what I remember. Luckily my name was not in the logs, I never worked on the engine!