Intrductin This leaflet cntains the required infrmatin t permit the straightfrward fitment f a Lithium Irn Phsphate (LifePO4) battery in place f standard lead acid battery in a BMAA aerplane. It permits nly certain ways f ding this, which are knwn t be straightfrward and minimise any risks. It des nt mean that there are nt ther ways f replacing yur battery, such as repsitining the battery, and if yu wish t d it anther way this must be dne thrugh a mre cnventinal md applicatin (at a ptentially greater cst) and mre infrmatin than is required here may be requested by the BMAA Technical Office. Ntwithstanding the simple apprach taken by this TIL, it is the aircraft wner s respnsibility t ensure that all materials used in a mdificatin are f adequate quality, that prper aircraft engineering standards are applied, that this mdificatin des nt create any safety prblem when cmbined with any ther mdificatin t the aircraft, and that n relevant infrmatin has been withheld frm the BMAA r Inspectr. Althugh the LiFePO4 battery chemistry is understd t be fairly safe, there is still unwillingness in the BMAA Technical Office (and CAA) t treat them in quite the same way as lead-acid batteries, which can be changed frm ne make and mdel t anther (reasnably equivalent make and mdel) withut explicit apprval. Anther imprtant reasn fr cntinued versight f lithium battery fitment is t ensure LiFePO4 batteries, and nt ther lithium-in batteries are being fitted. Ntes: The LiFePO4 chemistry is understd t be fundamentally fairly safe, particularly with regard t thermal runaway, which can be a significant prblem with ther lithium-in chemistries. Apparently the LiFePO4 chemistry des nt readily give up its xygen, even at high temperature, which is the cause f fire and explsin with ther lithium-in chemistries. LiFePO4 batteries have a significantly higher energy density than lead-acid batteries, which permits significant weight saving. LiFePO4 batteries have a very high pwer density even in cmparisn with ther lithium-in chemistries which makes them eminently suitable as starting batteries. Althugh the energy density f LiFePO4 batteries is nt as high as sme ther lithium-in batteries, this is nt critical fr a starting battery. Cnfusingly, the LiFePO4 chemistry smetimes just called lithium irn, r LiFe is ne f a number f lithium-in battery chemistries. Battery Apprval List Batteries currently cleared fr use n BMAA aircraft (nte that thers nt listed may als be cleared by the BMAA) Manufacturer Super B Aliant EarthX Varley Mdel SB12V5200, SB12V7800P X3P ETX18B Li-16, Li-5, Li-3 Page 1 f 7
Apprval basis fr LiFePO4 batteries The standard requirement fr batteries in BMAA aircraft is BCAR Sectin S requirement S1353. S1353 Strage battery design and installatin a) Each strage battery must be designed and installed as prescribed in this paragraph. b) N explsive r txic gases emitted by any battery in nrmal peratin, r as the result f any prbable malfunctin in the charging system r battery installatin, may accumulate in hazardus quantities within the aerplane. c) N crrsive fluids r gases that may escape frm the battery may damage surrunding structures r adjacent essential equipment. Fllwing discussins with the CAA, CS-23.1353 and a draft EASA Special Cnditin fr lithium batteries have been used fr guidance. Fr a starting battery, whse failure (t cntinue t prvide electricity) r manual discnnectin (frm the aircraft s electrical system) des nt unduly hazard the aircraft, the cnclusin drawn frm this guidance material was that, in additin t the existing requirements f S1353, a LiFePO4 battery shuld nt be unduly hazardus t aircraft r ccupants if accidentally shrt-circuited fr a prlnged perid (e.g. starter mtr slenid malfunctin), vercharged (e.g. rectifier malfunctin), r damaged in an accident. LiFePO4 BMAA apprval histry Previus BMAA apprvals f LiFePO4 batteries were n the fllwing basis: The battery was a LiFePO4 battery, nt anther type f lithium-in battery. The battery was marketed by the manufacturer as a replacement fr a lead-acid vehicle starting battery, and suitable fr charging with a nrmal vehicle charging system. The battery was nt unduly hazardus if accidentally shrt-circuited fr a prlnged perid (e.g. starter mtr slenid malfunctin). The battery was nt unduly hazardus if ver-charged (e.g. rectifier malfunctin). The battery was nt unduly hazardus if damaged in an accident. Fr the first tw BMAA apprvals shrt-circuit, ver-charge and accident damage tests were perfrmed by the applicants. The applicants made up their wn test specificatins. The batteries behaved very benignly, with n fire r explsin, and limited leaking r venting. Subsequent BMAA apprvals have been n the basis f UN DOT 38.3 certificatin, which requires the manufacturer t have demnstrated that the battery passes a number f tests including shrtcircuit, ver-charge and accident damage tests. UN DOT 38.3 Certificatin This certificatin is based n the United Natins requirements fr lithium battery testing prir t transprtatin: tinyurl.cm/p5j9fp. Tests are specified fr: 1. Altitude simulatin Page 2 f 7
2. Thermal test 3. Vibratin 4. Shck 5. External shrt circuit 6. Impact / crush 7. Overcharge 8. Frced discharge A rechargeable battery is subjected t tests 1 t 5 and 7. Its cnstituent cells are tested t at least tests 6 and 8. The nly real cncern that has been identified ver the applicability f the UN DOT 38.3 tests t BMAA aircraft is that the pass criteria fr the vercharge test are nly n disassembly (explsin) and n fire; rupture and venting are permissible. This vide shws that extreme vercharging can cause smke t be expelled, which culd be hazardus in an enclsed cckpit: tinyurl.cm/kqrxkef. Fr this reasn it is required that a vltmeter be fitted if a LiFePO4 battery is fitted inside an enclsed cckpit, and a means f islating the charging circuit shuld ver vltage ccur. The pass criteria fr the shrt-circuit test are n disassembly (explsin), n rupture and n fire, althugh venting is permissible (if the battery is designed t vent). The nly likely shrt circuit cnditin is a starter mtr slenid malfunctin which will tend t ccur n the grund. The vltmeter will give an indicatin f any shrt circuit cnditin. Standard Minr Mdificatin Apprval Requirements n an aircraft fr it t be suitable t be mdified (using the SMM): The aircraft is currently fitted with a lead-acid starting battery, which is t be replaced with a LiFePO4 starting battery. The lead-acid starting battery fitment is apprved. The aircraft s engine cntinues t run if the master switch is turned ff. If the battery is in an enclsed cckpit a vltmeter is fitted t mnitr charging. If the battery is in an enclsed cckpit there must be a means t islate the battery frm the charging system and the rest f the aircraft s DC system. A circuit breaker is an acceptable means f cmpliance. Requirements n a lithium battery fr it t be suitable as a direct replacement fr a lead-acid starting battery: The battery is a LiFePO4 battery, nt anther type f lithium-in battery, and marketed by the manufacturer as a replacement fr a lead-acid vehicle starting battery, and suitable fr charging with a nrmal vehicle charging system. UN DOT 38.3 Certificatin has been cnfirmed fr the LiFePO4 battery by the manufacturer t the satisfactin f the BMAA Technical Office. Requirements n the installatin (using the SMM): The aircraft s charging vltage meets the criteria prvided by the battery manufacturer. The battery manufacturer s installatin instructins are fllwed. The LiFePO4 battery is a suitable replacement in terms f vltage, starting current and capacity fr the existing lead-acid battery. The LiFePO4 battery is nt larger than the existing lead-acid battery. Page 3 f 7
The LiFePO4 battery fits in the same lcatin as the existing lead-acid battery. Mst batteries cme with additinal packing material t allw fr the smaller size f the LiFePO4 battery. A new r amended weight and balance reprt has been generated and is satisfactry. If a vltmeter is required, it is marked t shw an vercharge cnditin. If a charge islatin switch/circuit breaker is required it is marked fr peratin. Standard Minr Mdificatin cmpliance with apprval basis S23 S25 S597 Lad Distributin Limits Amended weight and balance reprt required. Weight Limits Replacement battery nt mre massive than apprved riginal. Lads frm Single Masses Replacement battery nt mre massive than apprved riginal. Replacement battery in same lcatin as apprved riginal. Changes t apprved installatin nt significant frm structural perspective. S1165 Engine Ignitin Systems Engine cntinues t run when islated frm battery. S1301 Equipment Functin and Installatin If there is a battery prblem and the pilt decides t islate the battery using the master switch, pwer t any EFIS will be lst. This is n different t any ther electrical prblem requiring the master switch t be turned ff. S1307 Miscellaneus Equipment Vltmeter required if battery in enclsed cckpit. S1353 Strage Battery Design and Installatin Battery has UN DOT 38.3 certificatin. Vltmeter required if battery in enclsed cckpit. Charging circuit required t be islated if battery in enclsed cckpit. Installatin essentially unchanged frm apprved riginal. S1365 Electric Cables and Equipment Unchanged frm apprved riginal. Imprtant Charging Nte Fllw the battery manufacturers guidelines fr charging each LiFePO4 battery. D nt use a standard lead-acid charger unless the manufacturer specifically says this is kay. Lead-acid chargers are ptimized fr a different battery technlgy and make use f methds fr charging and safeguarding which are nt always suitable fr LiFePO4 batteries. Page 4 f 7
Returning the Frm After fitting the battery, and having the mdificatin inspected by a BMAA Inspectr, the frm must be sent t the BMAA Technical Office fr apprval. It is acceptable t send in the frm with yur Permit revalidatin frm, nting in the mdificatins bx TIL 117 submitted. Prepared by: Apprved fr Issue: R Pattrick Design Apprval Engineer British Micrlight Aircraft Assciatin B J Sysn Chief Technical Officer British Micrlight Aircraft Assciatin Page 5 f 7
BMAA CHECKLIST:TIL 117 Reg: G- Owners name: Aircraft type: Serial N: Owners BMAA N: Battery Details N. ACTION COMMENTS Old Battery 1.1 Make and Mdel 1.2 Weight and Dimensins New Battery 1.3 Make and Mdel 1.4 Weight and Dimensins 1.5 Battery On BMAA Apprval List (If Battery Nt Listed Check With BMAA Technical Office Fr Apprval) Wt: Dims: Wt: Dims: INSPECTOR S INITIALS Safety Checks Installatin Checks 2.1 Battery Capabilities Suitable 2.2 Manufactures Instructins Available and Fllwed 2.3 Battery Fits Existing Bx 2.4 Battery Bx Lcatin 2.5 Any Packing Require If yes state what used. 2.6 Battery Nt In Clse Prximity (100mm r less) t any pwerful heat surce/s (i.e. manifld, exhaust system) 2.7 Battery Fitted Securely In Munt: Frward 9g, Upward 4.5g, Dwnward 4.5g & Sideward 3g. 2.8 Battery Cables Terminals Fit New Battery 2.9 Terminals adequately insulated and cnnected. 2.10 Weight Change 2.11 Estimated CG Change (3 axis) Frwards/Aft Still within limits. Fr batteries munted sme distance frm the CG i.e. twards the tail, aircraft shuld either be reweighed and reprt submitted with applicatin r the new cg calculated accurately. Page 6 f 7
Fr Battery Lcated In Enclsed Cckpit 3.1 Vltmeter Fitted and Marked Fr Overcharge Cnditin 3.2 Charging Circuit able t be islated. (Either switch r circuit breaker which can be pulled fr ff) 3.3 Switch/Circuit Breaker Placarded fr peratin Operatin 4.1 Cnduct Test Of Aircraft Starting System, satisfactry? 4.2 Master Switch Islates Battery Frm DC Circuits. Dcumentatin Fllwing dcuments t be kept with aircraft recrds: Manufacturer s fitting instructins; 5.1 Invices fr all parts; Crrespndence with BMAA Technical Office. 5.2 Mdificatin recrded in airframe lgbk. 5.3 Weight and balance reprt amended; mdified aircraft cntinues t cmply with the weight and balance requirements f the TADS / HADS. See 2.11 abve. OWNER S DECLARATION I declare that the freging infrmatin is crrect, and I will nt change the installatin design nce apprved. Signed: Name: Date: INSPECTOR S DECLARATION I declare that the freging infrmatin is crrect, the all requirements are cmplied with, and the installatin is fit t be flwn. Signed: Name: Insp N: Date: This frm must be sent with payment as per current fees in MF r www.bmaa.rg t*:- BMAA, The Bullring, Deddingtn, Banbury, Oxn, OX15 0TT BMAA Office Apprval: (signed) (Name) Md N.: G- / TIL117 / 20 / _ (Date) *Whilst waiting fr this frm t be returned by the BMAA the aircraft may be flwn fr upt ne calendar mnth frm the Inspectin date abve. Once this frm is returned t yu signed please enter the full mdificatin apprval number abve in yur aircraft lgbk and retain this sheet with yur aircraft recrds. Page 7 f 7