detail is everything Posted June 23, 2022 Share Posted June 23, 2022 (edited) Looking for help please from anyone with current RN Jungly Merlin knowledge. With the conversion from HC3A to HC4A, most external differences between the HC3/HC3A have gone, The UK HC3 had a four-tank fuel system compared to five for the former Danish HC3A, and the respective cockpit and window layouts were significantly different. Externally, the HC3A could be easily distinguished from the HC3 by its distinctive nose cone, which was designed to enable a laser obstacle avoidance system to be fitted in addition to a weather radar and electro-optical device. The MLSP eliminated most of the differences including the nose cone that was such a distinctive feature of the HC3A. In this respect, the engine and transmission rating structures and the nose mounted electro-optical/infrared device are now common for both types. Elsewhere, the HC4A received a hydraulic rescue hoist to replace the original electric hoist, the cabin port door now slides rather than pushes open and the cabin egress windows are now standardised across the fleet to the HC3 configuration to improve emergency egress. However, the HC4 retains the HC3 heavy-duty cabin floor and four-tank fuel system whereas the HC4A retains the HC3A standard floor and five-tank system. This means there are still some external differences between the HC4 and HC4A. For example on the port side, the number of external refuelling points on the HC4 are two and they seem to have covers. On the HC4A there are 3 external refuelling points which do not have any covers. I have it in my head that the external cargo carrying systems are also different, presumably linked to the different cabin floor specs, Is that right?. If I wanted to convert an HC4 to an HC4A, what other changes would I need to make? Any views or advice would be gratefully received. Edited June 23, 2022 by detail is everything typo Link to comment Share on other sites More sharing options...
wellsprop Posted June 24, 2022 Share Posted June 24, 2022 The Mk 4 has a cargo hook bay, whereas the Mk 4a does not (due to the aforementioned 5th tank). This means there's literally a hole in the bottom of the aircraft, seen here. Other than that, I can't immediately think of any external differences. 4 Link to comment Share on other sites More sharing options...
bootneck Posted June 24, 2022 Share Posted June 24, 2022 Lovely photo Ben, got any more? cheers, Mike Link to comment Share on other sites More sharing options...
wellsprop Posted June 25, 2022 Share Posted June 25, 2022 20 hours ago, bootneck said: Lovely photo Ben, got any more? cheers, Mike Not one of mine I'm afraid, most of mine tend to be from the inside looking out 😂 1 1 Link to comment Share on other sites More sharing options...
detail is everything Posted June 28, 2022 Author Share Posted June 28, 2022 (edited) So in the absence of any further advice, I have the following to add. Cargo hook As Ben says, the HC4 has a a cargo hook bay, in which the cargo hook is stored when not in use. Where as the HC4A does not. It has an externally stored hook which is held in place by four load bearing wires. This appears to be held up when not in use. Belly equipment There are also some detail differences with the belly equipment. I have found a good photo of an HC4 belly, but not for an HC4A though what I have seen confirms this. Edited June 28, 2022 by detail is everything sorted out hrts 2 Link to comment Share on other sites More sharing options...
detail is everything Posted July 13, 2022 Author Share Posted July 13, 2022 This is the best photo of the HC4A belly I can currently find. https://abpic.co.uk/pictures/model/AgustaWestland EH101 Merlin HC4A. It is in the Air Britain Photo Library Adjust the photo brightness and the detail becomes clearer. It can be seen that on the starboard side, there appears to be an extra belly search light forward in line with the secondary door and a couple of distinctive half circle air scoops just forward of the main undercarriage. On the port side there appears to be a further two belly search lights, one in line with the main door and one at the rear in line with the blade antenna which is on the starboard side. There are other detail differences. Link to comment Share on other sites More sharing options...
Ex-FAAWAFU Posted September 5, 2022 Share Posted September 5, 2022 That Mk4A load hook arrangement is essentially exactly the same as the SACRU and associated wires on the Sea King, by the look of it. And yes, it was held up when not in use. In the case of the Sea King, there was an arrangement on the port side through which a line was run and you could pull the SACRU etc up from inside the cab; you can see it on most Sea Kings because there is a tan coloured strip (to protect vs friction) with a pulley at the bottom. Look in the BM walkround section for Sea King HAS5 XZ574 at the FAA Museum; this tan thingy is clearly visible in the 9th & 10th photos as you scroll down. Don't know whether Merlin has same set up, but from the look if it, something similar. 1 Link to comment Share on other sites More sharing options...
wellsprop Posted September 12, 2022 Share Posted September 12, 2022 On 13/07/2022 at 11:30, detail is everything said: This is the best photo of the HC4A belly I can currently find. https://abpic.co.uk/pictures/model/AgustaWestland EH101 Merlin HC4A. It is in the Air Britain Photo Library Adjust the photo brightness and the detail becomes clearer. It can be seen that on the starboard side, there appears to be an extra belly search light forward in line with the secondary door and a couple of distinctive half circle air scoops just forward of the main undercarriage. On the port side there appears to be a further two belly search lights, one in line with the main door and one at the rear in line with the blade antenna which is on the starboard side. There are other detail differences. The 4 and 4A have the same lights and antennae (in the same positions). The 4A has an extra gravity refueling point (below the 2nd from the front cabin window - ignoring the window in the port forward door) - the 4's all appear to have covers over the gravity refilling points (the 4A's do not). All the 4A's have two letter identifiers, starting with A (i.e. 'AA' 'AB'). Both the 4's and 4A's, have covers on the upper fuselage, forward and below of the left and right engine intakes (there's a short and long rectangular cover). Obligatory disclaimer, all the above is obvious from published photographs. 1 Link to comment Share on other sites More sharing options...
detail is everything Posted September 13, 2022 Author Share Posted September 13, 2022 Thanks, I'd not noticed the extra panels forward and below of the left and right engine intakes. That's the sort of thing that is easily missed and only obvious if you know what to look for. 1 Link to comment Share on other sites More sharing options...
detail is everything Posted March 3, 2023 Author Share Posted March 3, 2023 On 9/13/2022 at 9:00 AM, detail is everything said: Thanks, I'd not noticed the extra panels forward and below of the left and right engine intakes. So I was at Yeovilton airbase yesterday, looking at a mixed row of HC4 and HC4As and the difference between the two variants in this area is obvious when you can compare and contrast. The HC4s at Yeovilton now have what appears to be an aerodynamic fairing or vent in front of the raised panels, which the HC4As currently do not have. The following is an HC4 with the fairings or vent. Photos of HC4s in this topic and on the internet show them without the fairings/vents, so this must be a recent addition. Perhaps someone who works on Merlins can clarify their purpose Link to comment Share on other sites More sharing options...
detail is everything Posted March 3, 2023 Author Share Posted March 3, 2023 (edited) Here are some earlier photos of HC4s without the fairing/vent in front of the raised panels. Edited March 4, 2023 by detail is everything 1 Link to comment Share on other sites More sharing options...
wellsprop Posted March 3, 2023 Share Posted March 3, 2023 The raised fairing/vent is not specific to the 4/4a, it can be fitted on either. Look at those slightly raised panels in detail; there is a long rectangular panel and a shorter rectangular panel (the shorter one being fore of the long panel), the slightly raised panels appear to be blanking panels. When those panels are installed, there is no fairing fitted - see below on a Mk4. The image below shows 3 equally sized rectangular boxes, that protrude significantly more than the raised panels - when these boxes are in place, it is evident the fairings (port and starboard) are in place. Again, obligatory disclaimer, all the above observations are made from images published on the following website https://www.seaforces.org/marint/Royal-Navy/AIRCRAFT/Merlin-HC4-RN.htm 1 Link to comment Share on other sites More sharing options...
detail is everything Posted March 3, 2023 Author Share Posted March 3, 2023 (edited) @wellsprop Many thanks for the clarification. When I was looking at the flight line yesterday, the HC4s had the fairings and the HC4As didn't. Clearly all the aircraft can have the boxes installed as they have the blanking panels. The fairings may well be fitted to the HC4As in due course (makes sense). Here's an HC4A with the boxes installed, but not the fairing. As you say, photos used for illustration purposes only. Edited March 3, 2023 by detail is everything 1 Link to comment Share on other sites More sharing options...
wellsprop Posted March 3, 2023 Share Posted March 3, 2023 Ah that's interesting, the fairing should be there and I'm fairly sure the Mk 4a has the provisions for the fairing. The fairing is there for a reason... I'll do some digging. Link to comment Share on other sites More sharing options...
Evalman Posted March 5, 2023 Share Posted March 5, 2023 (edited) Took me a while to work out where the fairing you mention is located. My most recent photos of Junglies were taken last May and when looking at the 4 and 4A together the fairing is definitely missing on the 4A. I've also just noticed that the 4A has a longer hand rail by the cabin door. Looking at older images the fairing only started to appear on the Mk 4 from 2021/22. Edited March 5, 2023 by Evalman 1 1 Link to comment Share on other sites More sharing options...
wellsprop Posted March 5, 2023 Share Posted March 5, 2023 2 hours ago, Evalman said: I've also just noticed that the 4A has a longer hand rail by the cabin door. I've never noticed that! I thought I was fairly well acquianted with the 4 and 4a, spent enough time clambering in and out of that door 😂 1 Link to comment Share on other sites More sharing options...
detail is everything Posted March 9, 2023 Author Share Posted March 9, 2023 On 6/28/2022 at 4:46 PM, detail is everything said: So in the absence of any further advice, I have the following to add. Cargo hook As Ben says, the HC4 has a a cargo hook bay, in which the cargo hook is stored when not in use. Where as the HC4A does not. It has an externally stored hook which is held in place by four load bearing wires. This appears to be held up when not in use. Belly equipment There are also some detail differences with the belly equipment. I have found a good photo of an HC4 belly, but not for an HC4A though what I have seen confirms this. Assuming much of the HC4A belly equipment is much the same (a few blade aerials will have changed) as that of the HC3A, this offers a comparison 1 Link to comment Share on other sites More sharing options...
shuck Posted March 11, 2023 Share Posted March 11, 2023 Have all 19 Merlin HC4 and six HC4A been modified with the automatic main rotor blade and tail folding system. Link to comment Share on other sites More sharing options...
detail is everything Posted March 12, 2023 Author Share Posted March 12, 2023 (edited) @wellspropwill probably be able to confirm but I would say all Merlins which went through the Merlin life sustainment programme (MLSP), will have had the mods you speak of. See Edited March 12, 2023 by detail is everything Link to comment Share on other sites More sharing options...
detail is everything Posted March 13, 2023 Author Share Posted March 13, 2023 (edited) Airframe details are as follows. It will be a little out of date, but I can't for the life of me, remember where it is on the internet Delivery reference Serial Mk Sqdn ident Current unit Current location Last movement Previous movements 50033/RAF01 ZJ117 HC3 A Whittle Hangar Gosport Jun 2022 r/o 25/11/1998, f/f 24/12/1998, d/d Boscombe Down 03/05/2002, d/d 31/05/2002, stored Boscombe Down, 50049/RAF02 ZJ118 HC4 B 845 NAS Yeovilton Dec 2021 f/f 14/06/1999, d/d Boscombe Down 19/01/2000 50075/RAF03 ZJ119 HC4 C MFSU Yeovilton Apr 2021 f/f 01/12/1999, d/d Boscombe Down 27/03/2002 50083/RAF04 ZJ120 HC4 D 845 NAS Yeovilton Dec 2021 f/f 30/03/2000, d/d 09/06/2003 50099/RAF05 ZJ121 HC4 E 845 NAS Yeovilton Dec 2021 f/f 14/06/2000, d/d 07/03/2001 50113/RAF06 ZJ122 HC4 F 845 NAS Yeovilton Oct 2020 f/f 26/06/2000, d/d 11/12/2000 50129/RAF07 ZJ123 HC4 G MDMF Culdrose Nov 2021 f/f 12/10/2000, d/d 01/05/2003 50133/RAF08 ZJ12 HC4 H 846 NAS Yeovilton May 2022 f/f 12/12/2000, d/d 12/01/2001 50137/RAF09 ZJ125 HC4 J QinetiQ Boscombe Down May 2022 f/f 21/12/2000, d/d 12/01/2001 50141/RAF10 ZJ126 HC4 K 846 NAS Yeovilton Jul 2021 f/f 18/12/2000, d/d 16/05/2001 50149/RAF11 ZJ127 HC4 L 845 NAS Yeovilton Dec 2021 f/f 29/03/2001, d/d 22/11/2001 50153/RAF12 ZJ128 HC4 M 845 NAS Yeovilton Mar 2022 f/f 29/03/2001, d/d 12/09/2001 50167/RAF13 ZJ129 HC4 N 845 NAS Yeovilton Dec 2021 f/f 09/05/2001, d/d 17/10/2001 50169/RAF14 ZJ130 HC4 O Upgrade Yeovil Airfield May 2022 f/f 28/06/2001, d/d 14/05/2002 50173/RAF15 ZJ131 HC4 P 845 NAS Yeovilton May 2021 f/f 30/07/2001, d/d 26/04/2002 50177/RAF16 ZJ132 HC4 Q Leonardo Yeovil Airfield Jul 2021 f/f 18/09/2001, d/d 29/01/2002 50181/RAF17 ZJ133 HC3 R Instructional hangar Brize Norton Mar 2022 f/f 29/10/2001, d/d 17/10/2002, stored Boscombe Down, 50183/RAF18 ZJ134 HC4 S 846 NAS Yeovilton Oct 2020 f/f 05/12/2001, d/d 01/03/2002 50187/RAF19 ZJ135 HC4 T Leonardo Yeovil Airfield Mar 2022 f/f 19/12/2001, d/d 22/03/2002 50191/RAF20 ZJ136 HC4 U 846 NAS Yeovilton Feb 2022 f/f 07/03/2002, d/d 29/04/2002 50195/RAF21 ZJ137 HC4 W 846 NAS Yeovilton Nov 2021 f/f 31/05/2002, d/d 21/08/2002 50199/RAF22 ZJ138 HC3 X 28 Sqn marks Private Scotland Jan 2022 f/f 30/09/2002, d/d 22/11/2002, w/o 23/06/2010, to private owner Scotland 2022 50089/DEN01 ZJ990 HC4A AA 846 NAS Yeovilton Nov 2021 f/f 12/12/2003, d/d 20/10/2006 to RDAF as M-501, rtnd to WHL 26/07/2007 50106/DEN03 ZJ992 HC4A AB 846 NAS Yeovilton Apr 2022 f/f 17/11/2004, d/d 08/03/2006 to RDAF as M-503, rtnd to WHL 12/07/2007, to RAF 50121/DEN05 ZJ994 HC4A AC 846 NAS Yeovilton Sep 2021 f/f 01/04/2005, d/d 02/02/2006 to RDAF as M-505, rtnd to WHL 12/07/2007, to RAF 50123/DEN06 ZJ995 HC4A AD 846 NAS Yeovilton Mar 2022 f/f 30/11/2005, d/d 29/04/2006 to RDAF as M-506, rtnd to WHL 26/07/2007, to RAF 50148/DEN09 ZJ998 HC4A AE 846 NAS Yeovilton Mar 2022 f/f 28/02/2006, d/d 16/06/2006 to RDAF as M-509, rtnd to WHL 29/06/2007, to RAF 50160/DEN11 ZK001 HC4A AF 846 NAS Yeovilton Jul 2021 f/f 05/06/2006, d/d 15/09/2006 to RDAF as M-511, rtnd to WHL 29/06/2007, to RAF f/f first flight d/d delivery date r/o rolled out Edited March 13, 2023 by detail is everything Link to comment Share on other sites More sharing options...
shuck Posted March 13, 2023 Share Posted March 13, 2023 9 hours ago, detail is everything said: @wellspropwill probably be able to confirm but I would say all Merlins which went through the Merlin life sustainment programme (MLSP), will have had the mods you speak of. See Apparently seven HC4 conversions were completed without the automatic folding main rotor head. I presume this is the seven initial embarked capability HC3i with manual blade fold. Merlin HC3i s/n ZJ118, ZJ126, ZJ130, ZJ132, ZJ135, ZJ136 and ZJ137 Link to comment Share on other sites More sharing options...
detail is everything Posted March 13, 2023 Author Share Posted March 13, 2023 (edited) 4 hours ago, shuck said: Apparently seven HC4 conversions were completed without the automatic folding main rotor head. I presume this is the seven initial embarked capability HC3i with manual blade fold. I find it doubtful that there would be a sub-set of airframes which are not consistent with the functionality of the rest. Possibly dedicated training airframes (the HC4As?) but then why not be consistent, for training purposes, with the front line machines? It would also reduce flexibility of fleet use, with, you would think all airframes embarked on ship, having the automatic folding main rotor head for consistency of aircraft operations. I would think the HC3is would have been brought up to HC4 standard eventually, but I could be wrong and would welcome confirmation either way. Edited March 13, 2023 by detail is everything Link to comment Share on other sites More sharing options...
wellsprop Posted March 13, 2023 Share Posted March 13, 2023 8 hours ago, shuck said: Apparently seven HC4 conversions were completed without the automatic folding main rotor head. I presume this is the seven initial embarked capability HC3i with manual blade fold. 4 hours ago, detail is everything said: I find it doubtful that there would be a sub-set of airframes which are not consistent with the functionality of the rest. Possibly dedicated training airframes (the HC4As?) but then why not be consistent, for training purposes, with the front line machines? It would also reduce flexibility of fleet use, with, you would think all airframes embarked on ship, having the automatic folding main rotor head for consistency of aircraft operations. I would think the HC3is would have been brought up to HC4 standard eventually, but I could be wrong and would welcome confirmation either way. All Merlin Mk 4 and 4a have the aircraft capability to fully fold https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/1140943/AAPWG_Paper_014.pdf The folding head is clearly distinguished by the split tension links on the main rotor head, the tension link fairings also have a cut-out in them to allow the rotors to fold. Here's the rotor head of an Italian Navy aircraft. Here's a Merlin Mk 4 without a folding head (see full tension link fairings). Obligatory disclaimer: All of this information is from the public domain. 2 Link to comment Share on other sites More sharing options...
detail is everything Posted March 14, 2023 Author Share Posted March 14, 2023 (edited) @wellsprop many thanks for pointing that out. So, to be clear, all Merlin Mk 4 and 4a have the capability to auto? fold their rotor heads if fitted with folding rotor heads, but they are not all fitted with folding rotor heads? Now you have shown what to look for, you can easily see which airframes have folding rotor heads. Looking at photos on the internet, None of the HC4As have been photographed with folding rotor heads All the iHC3s were fitted with folding rotor heads. However there are no photos of ZJ130 O and ZJ132 Q as HC4s and ZJ135 T and ZJ136 U have been photographed as HC4s with non-folding rotor heads (though this may have been a temporary fit since we are talking about one or two photos from a particular occasion in each case). All other HC4s have folding rotor heads with no photos showing them fitted with non-folding heads post HC3 to HC4 conversion. Edited March 14, 2023 by detail is everything Link to comment Share on other sites More sharing options...
wellsprop Posted March 14, 2023 Share Posted March 14, 2023 10 hours ago, detail is everything said: @wellsprop many thanks for pointing that out. So, to be clear, all Merlin Mk 4 and 4a have the capability to auto? fold their rotor heads if fitted with folding rotor heads, but they are not all fitted with folding rotor heads? Spot on. All the aircraft are built to the same standard and there are lots of bits and pieces of equipment that are fitted to some aircraft and not fitted to others - which is clear from photos (such as the camera, the DIRCM and the panels below and forward of the engine intakes, that we discussed earlier). Link to comment Share on other sites More sharing options...
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