[Xfire149]

I don't post here an awful lot but I do use the site for learning and I now have the opportunity to post something which others may find useful or of interest.

I was making an airways flight from Cambridge (the aircrafts home based airfield) to Newcastle. Around 1hr 10 mins into the flight, I was at FL110 at 33nm NNE of POL VOR, everything was totally normal when the engine suddenly lost all power. I looked down and saw that I was directly over the pennines (not ideal for a forced landing) which brought home how serious the situation was. I trimmed for best glide speed of 90Kts and carried out standard checks (change tanks, aux fuel pump on, left/right mags etc) but with no sign of life from the happily windmilling engine. I immediately declared an emergency with Scottish Control and requested vectors to “somewhere nicer to land” meaning flatter ground! They requested that I squawk 7700 gave me a heading for Teeside airfield which they informed me was 25nm away and gave me a handover frequency. Oh well, at least the ground was flatter towards Teeside than it was in Wensleydale! By the time I had contacted Teeside along with repeating the engine failure checks several times and double checking myself to see if I had missed anything, I was at 8000ft with 16 miles to run. I decided that the chances of making it to Teeside was not looking great so requested if there was anywhere closer - I was already scanning the now flatter terrain for a good landing site. Teeside approach informed me that they had spoken to RAF Leeming which was a little closer and they would accept me, they gave me a south easterly heading and a handover to Leeming which was around 10nm away. Leeming approach cleared me to land on any runway, and reported the ground wind was pretty much calm. I requested the longest runway which was 16/34 at 2289m, this was also pretty much inline with my approach heading of 140 (it doesn’t get much better than that!) I have never been so pleased to see a strip of tarmac appearing out of the haze. I had a little excess height to lose as I secured the engine for a power off approach and made an uneventful power off landing using about 400m of the runway.

I was met by several RAF fire tenders, ambulances, medics etc which was very reassuring but thankfully not necessary on this occasion. The RAF were fantastic (once they had determined I was not a security threat) and offered me coffee, breakfast, use of the pilots facilities and organised for Graham Fox who runs Flying Fox Aviation at nearby Bagby airfield and two engineers to fly in (in a Cessna 172) and look at the Mooney. Graham diagnosed that both magnetos had detached themselves from the back of the engine and the single auxillary driveshaft that powered them both. The mags on this particular variant of the Lycoming io-360 engine are housed in one unit and driven by a single shaft, the whole unit is held in place by two threaded studs, clamps and retaining nuts. The most likely explanation is that one of the retaining nuts had come loose (they are not lockwired) and the mag unit had spun around shattering the other clamp and the housing.

Graham flew me back to Bagby with his engineers in the C172 where we drew up a plan to get a new mag unit on order and (the icing on the cake) lent me a C150 to get home and said we could keep it until the mooney is repaired.

I’m pretty sure that Carlsberg don’t provide facilities for emergency landings and aircraft repairs, but if they did it would struggle to compete with the excellent service received from Scottish Control, Teeside Approach, RAF Leeming Ops, 100 Squadron & Graham Fox Aircraft Engineering (Flying Fox) Ltd of Bagby. A huge thanks to all that made that worst day not so bad after all.

[townleyc]

Good write up, and well done in the first place. Aviation is sometimes like that - so many people will just help.

Good on them!

KE

[Flyin'Dutch']

Bloody good end to an engine failure!

Well done to you and fantastic that so many people and organisations were happy to help you.

Heart warming!

[rf3flyer]

Good outcome to an uncomfortable situation, well done all involved.
It would be interesting to learn why the nuts came off. Since they are not wirelocked I assume they are one of the variety of stiffnuts. Reused?

[mick w]

Good outcome to an uncomfortable situation, well done all involved.
It would be interesting to learn why the nuts came off. Since they are not wirelocked I assume they are one of the variety of stiffnuts. Reused?

Normally plain Nuts on Mags .

[GrahamB]

Interesting. Some friends of mine have just bought a PA28 Dakota with a similar single mag casing arrangement. They have already had some issues with the mag casing having been worn away at the point where the mounting block tightens up against it, resulting in the casing effectively only being held firm on one side.

Well done for the cool head btw!

[rf3flyer]

Anyone know the glide ratio for a Mooney M20J? Googling seems to suggest 12:1 or 13:1 though I cannot find anything definitive.

In still air 25Nm to Teeside from FL110 would require a glide ratio of nearly 14:1. At 16Nm and 8000ft the required glide ratio is down closer to 12:1 so something was working in Xfire's favour.

A windmilling prop is more draggy than a stopped prop. Online 'wisdom' seems to suggest it degrades the Mooney's glide ratio to maybe 10:1 so to have achieved what Xfire did by 8000ft there must have been a tailwind component in play or the Mooney has a better glide ratio than I think is likely, either of which suggests that Teeside may just have been doable. That said, I'd have gone for the Leeming option myself.

[cockney steve]

I find it really odd, the apparently arbitrary way components are selected to be wire-locked, or not.

Mags and cylinders are both pretty vital to an engine's continued function. I know of a 172 Cessna that threw a jug off a zero-time engine at less than 100 hours I thought the torque settings on the nuts to be on the low side....ditto,Alternator output terminals, little more than finger-tight and a tweak....you could tighten another 1/2 turn without stretching the threads (and it would save all those burnt terminal-posts and premature failures ) What's with lockwire anyway? In the 21st. Century, the use of thread-locking compounds in critical applications, is well proven.
To mandate a pair of mags being held on with just 2 nuts sounds like a reckless disregard of user-safety and best practice. Perhaps I'm wrong, perhaps locking tab-washers / shakeproof washers, locktite or wiring was specified, but omitted.
Perhaps a build- technique review of these archaic engines is long overdue?

Great story from the OP who got out of a jam he should never have been put in in the first place.
Above is just my biased opinion. I am a (retired) motor- mechanic, not a Pilot.

[rf3flyer]

...What's with lockwire anyway? In the 21st. Century, the use of thread-locking compounds in critical applications, is well proven.

One easy way to fail a joint with thread locking compound is to heat it. A couple of nuts on the back of a crankcase? I wouldn't be confident. Wire locking doesn't suffer from that plus it's light, simple and easy to visually check.

[Xfire149]

Regarding glide ratio - I didn't make Teeside and had to divert to Leeming. I had a slight headwind and glided 20nm from FL110 arriving at Leeming with 2500ft spare! 2nm/1000ft (approx 12:1) in still air is the rule of thumb I will use from now on. Incidentally, when I pulled the prop lever back to full coarse (as the prop was windmilling) - the glide ratio significantly improved (I was never taught this on any complex rating or flight test but something I read and tried - it definitely helped a lot!)

[cockney steve]

Wire locking doesn't suffer from that plus it's light, simple and easy to visually check.

Certainly can't argue with that!

One easy way to fail a joint with thread locking compound is to heat it. A couple of nuts on the back of a crankcase? I wouldn't be confident.

I'd be a lot less confident with buggerall there, as the OP's experience has demonstrated. A crankcase just won't get hot enough to soften the correct grade, to the point of ineffectiveness.. Around 1969, I had a Viva 1600 with the GM OHC engine tipped over ~45* . Exhaust-manifold nuts were secured by stainless-steel tab-washers......they failed every 1K miles or so (weekly!) Sent the Loctite rep to the garage, never had another problem with the manifold falling off..

With something as critical as a complete ignition-system, I'd really want some sort of secondary security.
Relying on perfect, clean, undamaged thread-profiles with "to the book" friction-characteristics and an operative with the time and inclination to tighten those fastenings in the approved manner, in order to get the correct loading , is really pushing it....a chemical locking-compound can compensate for a lot of these cumulative flaws on the process, without making any visible modification.

Another,seemingly abandoned method, is to use a locknut.Not seen one in a modern application, for years.

[Dodo]

I think you did brilliantly. From a psychological point of view I would be interested to know whether your thought processes were as cool and logical as they appear or whether fear/anxiety etc. clouded, or indeed, sharpened your thinking. Don't answer if you don't want to.

[Xfire149]

Dodo - From a psychological point of view, I had a brief period of 'refusal to acknowledge it was happening' but I had already gone into autodrive with trimming for best glide and immediate basic checks, this used me to be slower than I should've been declaring the emergency with ATC. I did have an "oh sh*t" moment when I realised where I was and didn't know that I could glide clear of the pennines! The time I had in the glide was easily enough to fully accept the situation and Leemings runway coming into sight was a massive confidence booster that this may not end so bad after all. A landing in even a reasonably good but unprepared landing area in a Mooney is unlikely to be very pretty!

[Dodo]

Thank you Xfire149. That is very interesting (and in a way as helpful as the technical discussion). Dodo

[Charles Hunt]

Wow. Excellent outcome and well done.