Sourced From Aero-news.net Website Important Info About Vg's

[Guest Michael Coates]

please read the following report as sourced from the aero-news.net website..... then, my comments are beneath the article.

 

NTSB Prelim: Experimental Skyboy Had UnderGone MX Just Before Fatal Spins

 

MX and Wings Mods Being Investigated

 

You can rarely overdo the process of checking up on an airframe after maintenance... and while there are some pretty ponderous questions over what occurred in this fatal accident, the fact that it took place while checking up after recent maintenance does create some suspicions. We look forward to the final report on this accident.

 

 

NTSB Identification: ERA12FA052

 

14 CFR Part 91: General Aviation

 

Accident occurred Saturday, October 29, 2011 in Homestead, FL

 

Aircraft: INTERPLANE S R O SKYBOY, registration: N58784

 

Injuries: 2 Fatal.

 

This is preliminary information, subject to change, and may contain errors. Any errors in this report will be corrected when the final report has been completed.

 

On October 29, 2011, about 1022 eastern standard time, an experimental light sport aircraft (E-LSA), Czech Republic, Interplane SRO Skyboy, airplane, N58784, registered and operated by an individual, incurred substantial damaged from ground impact at Richards Field Airport (04FA), Miami, Florida. Both pilots on board were killed. Visual meteorological conditions prevailed at the time and no flight plan was filed for the Title 14 Code of Federal Regulations, Part 91 personal flight. The flight originated from the same airport earlier that day, about 0940.

 

 

 

 

 

 

 

 

 

 

 

Witnesses stated that the pilot had performed mechanical work on the airplane during the weeks prior to the accident flight. Earlier that morning he conducted a maintenance test flight, which included several touch and goes and stalls. The airplane had vortex generators installed on the wings as part of the maintenance work. There was a second pilot that was assisting the test flight pilot with the maintenance efforts on the airplane. During the initial test flight she remained on the ground with a radio monitoring the test flight progress. There were no abnormalities identified during this test flight. The pilot landed. The assisting pilot and the test flight pilot both got into the airplane to go fly. The airplane was in the air for about thirty to forty minutes conducting touch and goes, stalls, and air work in the vicinity of the private airstrip. Witnesses observed the airplane flying at slow speed in a north east direction, at an estimated altitude of 300 feet above ground level. As the airplane approach the airport it was observed entering a spin in a near full nose down attitude. The airplane completed three spins before it impacted the ground Witnesses made comments that the engine was running during the flight including the spin.

 

A global position system (GPS) unit, which was recovered among the wreckage, and a flight control component were retained by NTSB for further examination.

 

xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx

 

firstly, let me say that my comments have nothing to do with the sky boy aircraft (which is no longer even being manufactured).

 

The importance of me highlighting this article is based around the addition of vortex generators or VG's to an aircraft without a full flight program.

 

I have seen many many times aviators simply sticking these things all over their aircraft without the knowledge about what they are doing all the effects that this can cause and it looks in this occasion like they have affected the stall enough that the aircraft and had a spin with fatal results.

 

VG's if correctly fitted and confirmed their position by a complete and thorough test plane can offer some aircraft important and valuable improvements in performance and control ability, incorrectly fitted they can turn a pussycat into a tiger and the fitting of these devices to any airframe must be fully considered to make this aircraft a true experimental and you are becoming a test pilot as such.

 

I must say this is about the third report I have read of people fitting VG's to their aircraft with fatal results..... whilst they are currently flavour of the month it is really important to contact your aircraft manufacturer to their opinion and experience and if your aircraft is factory built they cannot be fitted without an engineering report for aircraft registered in some categories or for aircraft registered in the LSA category permission from the manufacturer along with a supplemental certificate and a statement of continuing compliance.

 

Please heed the NTSB report above

 

 

[cficare]

I am continually concerned with the use of VG's on a (very ageing) fleet of Piper Cheiftains.

 

Sure they increase the MTOW....but...in a failed engine scenario..they are a recipe for disaster...increased drag ...less single engine performance..

 

 

[Old Koreelah]

I am continually concerned with the use of VG's on a (very ageing) fleet of Piper Cheiftains.Sure they increase the MTOW....but...in a failed engine scenario..they are a recipe for disaster...increased drag ...less single engine performance..

Hello CFI, interested in your comment, having glued VG's along my Jodel D9 wing. The testing I've done suggests a 4-5% reduction in stall speed at altitude. The stall doesn't seem to be any more sudden that before. Beyond a small drag penalty if I have to glide, is there any other potential problem that could bite me?

 

 

[geoffreywh]

The only thing (in my opinion) that could bite you is uniformed comment by people that have no business putting such ideas in good people's heads. I quote such an uninformed opinion ".but...in a failed engine scenario..they are a recipe for disaster...increased drag".................................... where in hell did the theory of "increased drag " in isolation come from?????? At a given A of A they (VG's) may increase lift by factor x4 while increasing drag at a factor x2 so, forgive me, but I would LOVE to have reduced ground speed to the tune of 5 or so knots in an engine out situation... MY lowest landing speed seen so far is in the low 30's as against 40+ pre VG installation..(notwithstanding the vagaries of slow speed ASI indication) ....That means about 50% less kinetic energy to disapate in the touchdown...That is NOT a recipe for disaster..It's a potential life saver. In the crash report it states that Mechanical work was performed in weeks prior to the crash. Why did the author jump on the VG's and ignore the "mechanical maintenance" That could have been anything, New elevator cables maybe, why are VG's at fault???? The report also states the the aircraft was seen in a FULL nose down attitude at slow speed! Looks awfully like a stall and spin incident to me.and VG's are not going to save you there.......For more look at the STOL SPEED website